Plastic eyeglass lenses

ABSTRACT

An apparatus for preparing a plastic eyeglass lens includes a coating unit and a lens curing unit. The apparatus is preferably configured to allow the operation of both the coating unit and the lens curing unit. The apparatus may also include a post-cure unit and a controller. The controller is configured to control the operation of the coating unit, the lens curing unit and the post-cure unit. The lens forming unit may include an LCD filter disposed between activating light sources and a mold assembly. The mold assembly preferably includes two mold members held together by a gasket. The gasket preferably includes four protrusions spaced at 90 degree intervals about the gasket. A lens forming composition may include a first photochromic compound, a second photochromic compound and a light effector. The light effector may alter the color of a lens when exposed to photochromic activating light, when compared to a lens formed from a lens forming composition which does not include a light effector.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates generally to eyeglass lenses. Moreparticularly, the invention relates to a lens forming composition,system and method for making photochromic, ultraviolet/visible lightabsorbing, and colored plastic lenses by curing the lens formingcomposition using activating light.

[0003] 2. Description of the Relevant Art

[0004] It is conventional in the art to produce optical lenses bythermal curing techniques from the polymer of diethylene glycolbis(allyl)-carbonate (DEG-BAC). In addition, optical lenses may also bemade using ultraviolet (“UV”) light curing techniques. See, for example,U.S. Pat. No. 4,728,469 to Lipscomb et al., U.S. Pat. No. 4,879,318 toLipscomb et al., U.S. Pat. No. 5,364,256 to Lipscomb et al., U.S. Pat.No. 5,415,816 to Buazza et al., U.S. Pat. No. 5,529,728 to Buazza etal., U.S. Pat. No. 5,514,214 to Joel et al., U.S. Pat. No. 5,516,468 toLipscomb, et al., U.S. Pat. No. 5,529,728 to Buazza et al., U.S. Pat.No. 5,689,324 to Lossman et al., and U.S. patent application Ser. No.07/425,371 filed Oct. 26, 1989, Ser. No. 08/439,691 filed May 12, 1995,Ser. No. 08/454,523 filed May 30, 1995, Ser. No. 08/453,770 filed May30, 1995, Ser. No. 08/636,510 filed Apr. 19, 1996, Ser. No. 08/663,703filed Jun. 14, 1996, Ser. No. 08/666,062 filed Jun. 14, 1996, Ser. No.08/853,134 filed May 8, 1997, Ser. No. 08/844,557 filed Apr. 18, 1997,Ser. No. 08/904,289 filed Jul. 31, 1997, and Ser. No. 08/959,973 filedOct. 29, 1997, all of which are hereby specifically incorporated byreference.

[0005] Curing of a lens by ultraviolet light tends to present certainproblems that must be overcome to produce a viable lens. Such problemsinclude yellowing of the lens, cracking of the lens or mold, opticaldistortions in the lens, and premature release of the lens from themold. In addition, many of the useful ultraviolet light-curable lensforming compositions exhibit certain characteristics that increase thedifficulty of a lens curing process. For example, due to the relativelyrapid nature of ultraviolet light initiated reactions, it is a challengeto provide a composition that is ultraviolet light curable to form aneyeglass lens. Excessive exothermic heat tends to cause defects in thecured lens. To avoid such defects, the level of photoinitiator may bereduced to levels below what is customarily employed in the ultravioletcuring art.

[0006] While reducing the level of photoinitiator addresses someproblems, it may also cause others. For instance, lowered levels ofphotoinitiator may cause the material in regions near an edge of thelens and proximate a gasket wall in a mold cavity to incompletely curedue to the presence of oxygen in these regions (oxygen is believed toinhibit curing of many lens forming compositions or materials). Uncuredlens forming composition tends to result in lenses with “wet” edgescovered by sticky uncured lens forming composition. Furthermore, uncuredlens forming composition may migrate to and contaminate the opticalsurfaces of the lens upon demolding. The contaminated lens is then oftenunusable.

[0007] Uncured lens forming composition has been addressed by a varietyof methods (see, e.g., the methods described in U.S. Pat. No. 5,529,728to Buazza et al). Such methods may include removing the gasket andapplying either an oxygen barrier or a photoinitiator enriched liquid tothe exposed edge of the lens, and then re-irradiating the lens with adosage of ultraviolet light sufficient to completely dry the edge of thelens prior to demolding. During such irradiation, however, higher thandesirable levels of irradiation, or longer than desirable periods ofirradiation, may be required. The additional ultraviolet irradiation mayin some circumstances cause defects such as yellowing in the lens.

[0008] The low photoinitiator levels utilized in many ultravioletcurable lens forming compositions may produce a lens that, whilefully-cured as measured by percentage of remaining double bonds, may notpossess sufficient cross-link density on the lens surface to providedesirable dye absorption characteristics during the tinting process.

[0009] Various methods of increasing the surface density of suchultraviolet light curable lenses are described in U.S. Pat. No.5,529,728 to Buazza et al. In one method, the lens is de-molded and thenthe surfaces of the lens are exposed directly to ultraviolet light Therelatively short wavelengths (around 254 nm) provided by someultraviolet light sources (e.g., a mercury vapor lamp) tend to cause thematerial to cross-link quite rapidly. An undesirable effect of thismethod, however, is that the lens tends to yellow as a result of suchexposure. Further, any contaminants on the surface of the lens that areexposed to short wavelengths of high intensity ultraviolet light maycause tint defects.

[0010] Another method involves exposing the lens to relatively highintensity ultraviolet radiation while it is still within a mold cavityformed between glass molds. The glass molds tend to absorb the moreeffective short wavelengths, while transmitting wavelengths of about 365nm. This method generally requires long exposure times and often theinfrared radiation absorbed by the lens mold assembly will causepremature release of the lens from a mold member. The lens mold assemblymay be heated prior to exposure to high intensity ultraviolet light,thereby reducing the amount of radiation necessary to attain a desiredlevel of cross-link density. This method, however, is also associatedwith a higher rate of premature release.

[0011] It is well known in the art that a lens mold/gasket assembly maybe heated to cure the lens forming composition from a liquid monomer toa solid polymer. It is also well known that such a lens may be thermallypostcured by applying convective heat to the lens after the molds andgaskets have been removed from the lens.

[0012] In this application the terms “lens forming material” and “lensforming compositions” are used interchangeably.

SUMMARY OF THE INVENTION

[0013] An embodiment of an apparatus for preparing an eyeglass lens isdescribed. The apparatus includes a coating unit and a lens curing unit.The coating unit may be configured to coat either mold members orlenses. Preferably, the coating unit is a spin coating unit The lenscuring unit may be configured to direct activating light toward moldmembers. The mold members are part of a mold assembly that may be placedwithin the lens curing unit. Depending on the type of lens formingcomposition used, the apparatus may be used to form photochromic andnon-photochromic lenses. The apparatus is preferably configured to allowthe operation of both the coating unit and the lens curing unitsubstantially simultaneously.

[0014] The coating unit is preferably a spin coating unit. The spincoating unit preferably comprises a holder for holding an eyeglass lensor a mold member. The holder is preferably coupled to a motor that ispreferably configured to rotate the holder. An activating light sourcemay be incorporated into a cover. The cover may be drawn over the bodyof the lens curing unit, covering the coating units. The activatinglight source is preferably positioned, when the cover is closed, suchthat activating light may be applied to the mold member or lenspositioned within the coating unit An activating light source may be anultraviolet light source, an actinic light source (e.g., a light sourceproducing light having a wavelength between about 380 nm to 490 nm), avisible light source and/or an infra-red light source. Preferably, theactivating light source is an ultraviolet light source.

[0015] The lens curing unit includes at least one, preferably twoactivating light sources for irradiating a mold assembly. Mold assemblyholders may be positionable within the lens forming apparatus such thatthe activating light may be applied to the mold member during use. Afilter is preferably positioned between the mold assemblies and theactivating light source. The filter is preferably configured tomanipulate the intensity of activating light that is directed toward themold members. The filter may be a hazy filter that includes a frostedglass member. Alternatively, the filter may be a liquid crystal display(“LCD”) panel.

[0016] An LCD panel for use as a filter is preferably a monochrometrans-flective panel with the back light and reflector removed. Theintensity of the light is preferably reduced as the light passes throughthe LCD panel. The LCD panel is preferably programmable such that thelight transmissibility of the LCD panel may be altered. In use, apredetermined pattern of light and dark regions may be displayed on theLCD panel to alter the intensity of light passing through the panel. Oneadvantage of an LCD panel filter is that a pattern may be altered duringa curing cycle. For example, the pattern of light and dark regions maybe manipulated such that a lens is initially cured from the center ofthe lens, then the curing may be gradually expanded to the outer edgesof the lens. This type of curing pattern may allow a more uniformlycured lens to be formed.

[0017] Another advantage is that the LCD panel may be used as a partialshutter to reduce the intensity of light reaching the mold assembly. Byblackening the entire LCD panel the amount of light reaching any portionof the mold assembly may be reduced. In this manner, the LCD may be usedto create “pulses” of light by alternating between a transmissive anddarkened mode.

[0018] In another embodiment, an LCD panel may be used to allowdifferent patterns and/or intensities of light to reach two separatemold assemblies. If the mold assemblies are being used to create lenseshaving significantly different powers, each mold assembly may require asignificantly different light irradiation pattern and/or intensity. Theuse of an LCD filter may allow the irradiation of each of the moldassemblies to be controlled individually.

[0019] When non-LCD type filters are used, it may be necessary tomaintain a library of filters for use in the production of differenttypes of prescription lenses. Typically, each individual prescriptionwill need a particular filter pattern to obtain a high quality lens.Since an LCD panel is programmable in a variety of patterns, it isbelieved that one may use a single LCD panel, rather than a library offilters. The LCD panel may be programmed to fit the needs of thespecific type of lens being formed.

[0020] The LCD panel filters may be coupled to a programmable logicdevice that may be used to design and store patterns for use duringcuring. FIG. 7-10 show a number of patterns that may be generated on anLCD panel and used to filter activating light. Each of these patterns ispreferably used for the production of a lens having a specificprescription power.

[0021] The lens forming apparatus may include a post-cure unit. Thepost-cure unit is preferably configured to apply heat and activatinglight to mold assemblies or lenses disposed within the post-cure unit.

[0022] The lens forming apparatus may also include a programmablecontroller configured to substantially simultaneously control theoperation of the coating unit, the lens curing unit and the post-cureunit. The apparatus may include a number of light probes and temperatureprobes disposed within the coating unit, lens curing unit, and thepost-cure unit. These probes preferably relay information about theoperation of the individual units to the controller. The informationrelayed may be used to control the operation of the individual units.The operation of each of the units may also be controlled based on theprescription of the lens being formed.

[0023] The controller may be configured to control various operations ofthe coating unit. For example, when a spin coating unit is used thecontroller may control the rotation of the lens or mold member during acoating process (e.g., whether the lens or mold members are rotated ornot and/or the speed of rotation) and the operation of the coating unitlamps (e.g., whether the lamps are on or off and/or the time the lampsare on).

[0024] The controller may also be configured to control the variousoperations of the lens curing unit. Some of the operations that may becontrolled or measured by the controller include: (i) measuring theambient room temperature; (ii) determining the dose of light (or initialdose of light in pulsed curing applications) required to cure the lensforming composition, based on the ambient room temperature; (iii)applying the activating light with an intensity and duration sufficientto equal the determined dose; (iv) measuring the composition'stemperature response during and subsequent to the application of thedose of light; (v) calculating the dose required for the nextapplication of activating light (in pulsed curing applications); (vi)applying the activating light with an intensity and duration sufficientto equal the determined second dose; (vii) determining when the curingprocess is complete by monitoring the temperature response of the lensforming composition during the application of activating light; (viii)turning the upper and lower light sources on and off independently; (ix)monitoring the lamp temperature, and controlling the temperature of thelamps by activating cooling fans proximate the lamps; and (x) turningthe fans on/off or controlling the flow rate of an air stream producedby a fan to control the composition temperature;

[0025] The controller may also be configured to control the operation ofthe post-cure unit. Some of the operations that may be controlledinclude control of the operation of the lamps (e.g., whether the lampsare on or off and the time the lamps are on); and operation of theheating device (e.g., whether the heating unit is turned on or offand/or the amount of heat produced by the heating device).

[0026] Additionally, the controller provides system diagnostics andinformation to the operator of the apparatus. The controller may notifythe user when routine maintenance is due or when a system error isdetected. The controller may also manage an interlock system for safetyand energy conservation purposes. The controller may prevent the lampsfrom operating when the operator may be exposed to light from the lamps.

[0027] The controller may also be configured to interact with theoperator. The controller preferably includes an input device and adisplay screen. A number of operations controlled by the controller, asdescribed above, may be dependent on the input of the operator. Thecontroller may prepare a sequence of instructions based on the type oflens (clear, ultraviolet/visible light absorbing, photochromic, colored,etc.), prescription, and type of coatings (e.g., scratch resistant,adhesion promoting, or tint) inputted by an operator.

[0028] A variety of lens forming compositions may be cured to form aplastic eyeglass lens in the above described apparatus. Colored lenses,photochromic lenses, and ultraviolet/visible light absorbing colorlesslenses may be formed. The lens forming compositions may be formulatedsuch that the conditions for forming the lens (e.g., curing conditionsand post cure conditions) may be similar without regard to the lensbeing formed. In an embodiment, a clear lens may be formed under similarconditions used to form photochromic lenses by adding a colorless,non-photochromic ultraviolet/visible light absorbing compound to thelens forming composition. The curing process for forming a photochromiclens is such that higher doses of activating light than are typicallyused for the formation of a clear, non-ultraviolet/visible lightabsorbing lens may be required. In an embodiment, ultraviolet/visiblelight absorbing compounds may be added to a lens forming composition toproduce a substantially clear lens under the more intense dosingrequirements used to form photochromic lenses. The ultraviolet/visiblelight absorbing compounds may take the place of the photochromiccompounds, making curing at higher doses possible for clear lenses. Anadvantage of adding the ultraviolet/visible light absorbers to the lensforming composition is that the clear lens formed may offer betterprotection against ultraviolet/visible light rays than a clear lensformed without such compounds.

[0029] An embodiment relates to an improved gasket for engaging a mold.The gasket is preferably configured to engage a first mold set forforming a first lens of a first power. The gasket preferably includes atleast four discrete projections for spacing mold members of a mold set.The projections are preferably arranged on an interior surface of thegasket. The projections are preferably evenly spaced around the interiorsurface of the gasket; in a preferred embodiment, the spacing betweeneach projection is about 90 degrees.

[0030] In another embodiment, an improved gasket includes a fill portfor receiving a lens forming composition while fully engaged to a moldset. The fill port preferably extends from an interior surface of thegasket to an exterior surface of the gasket. Consequently, the gasketneed not be partially disengaged from a mold member of a mold set inorder to receive a lens forming composition.

[0031] In another embodiment, a mold/gasket assembly for making plasticprescription lenses preferably includes a first mold set for forming afirst lens of a first power and a gasket for engaging the first moldset. The first mold set may contain a front mold member and a back moldmember. The back mold member is also known as the convex mold member.The back mold member preferably defines the concave surface of a convexlens. The gasket is preferably characterized by at least four discreteprojections for spacing the front mold member from the back mold member.A mold cavity for retaining a lens forming composition is preferably atleast partially defined by the front mold member, the back mold member,and the gasket. The back mold member preferably has a steep axis and aflat axis. Each of the projections preferably forms an oblique anglewith the steep and the flat axis of the mold members. In a preferredembodiment, these angles may each be about 45 degrees. Since the gasketdoes not include a continuous lip along its interior surface for spacingmold members, as is conventional in the art, the gasket may beconfigured to engage a large variety of mold sets. For example, thegasket may be configured to engage a second mold set for forming asecond lens of a second power.

[0032] In another embodiment, a mold/gasket assembly for making plasticprescription lenses includes a mold set for forming a lens and a gasketconfigured to engage the mold set. The gasket is preferablycharacterized by a fill port for receiving a lens forming compositionwhile the gasket is fully engaged to the mold. The fill port preferablyextends from an interior surface to an exterior surface of the gasket.The mold set preferably contains at least a front mold member and a backmold member. A mold cavity for retaining a lens forming composition ispreferably at least partially defined by the front mold member, the backmold member, and the gasket.

[0033] A method for making a plastic eyeglass lens is described. Themethod preferably includes engaging a gasket with a first mold set forforming a first lens of a first power. The first mold set preferablycontains at least a front mold member and a back mold member. A moldcavity for retaining a lens forming composition may be at leastpartially defined by the front mold member, the back mold member, andthe gasket. The gasket is preferably characterized by at least fourdiscrete projections arranged on an interior surface thereof for spacingthe front and back mold members. Engaging the gasket with the mold setpreferably includes positioning the back mold members such that each ofthe projections forms an oblique angle with the steep and flat axis ofthe back mold member. In a preferred embodiment, this angle is about 45degrees. The method preferably further includes introducing a lensforming composition into the mold cavity and curing the lens formingcomposition.

[0034] An additional embodiment provides a method for making a plasticeyeglass lens. The method preferably includes engaging a gasket with afirst mold set for forming a first lens of a first power. The first moldset preferably contains at least a front mold member and a back moldmember. A mold cavity for retaining a lens forming composition may be atleast partially defined by the front mold member, the back mold member,and the gasket. Preferably, the method further includes introducing alens forming composition through a fill port, wherein the front and backmold members remain fully engaged with the gasket during theintroduction of the lens forming composition. The lens formingcomposition may then be cured.

[0035] In an embodiment, a composition that includes two or morephotochromic compounds may further include a light effector compositionto produce a lens that exhibits an activated color that differs from anactivated color produced by the photochromic compounds without the lighteffector composition. The activated color is defined as the color a lensachieves when exposed to a photochromic activating light source (e.g.,sunlight). A photochromic activating light source is defined as anylight source that produces light having a wavelength that causes aphotochromic compound to become colored. Photochromic activating lightis defined as light that has a wavelength capable of causing aphotochromic compound to become colored. The photochromic activatingwavelength band is defined as the region of light that has a wavelengththat causes coloring of photochromic compounds. The light effectorcomposition may include any compound that exhibits absorbance of atleast a portion of the photochromic activating wavelength band. Lighteffector compositions may include photoinitiators, ultraviolet/visiblelight absorbers, ultraviolet light stabilizers, and dyes. In thismanner, the activated color of a lens may be altered without alteringthe ratio and or composition of the photochromic compounds. By using alight effector composition, a single lens forming composition may beused as a base solution to which a light effector may be added in orderto alter the activated color of the formed lens.

[0036] The addition of a light effector composition that absorbsphotochromic activating light may cause a change in the activated colorof the formed lens. The change in activated color may be dependent onthe range of photochromic activating light absorbed by the lighteffector composition. The use of different light effector compositionsmay allow an operator to produce photochromic lenses with a wide varietyof activated colors (e.g., red, orange, yellow, green, blue, indigo,violet, gray, or brown).

[0037] In an embodiment, an ophthalmic eyeglass lens may be made from anactivating light curable lens forming composition comprising a monomercomposition and a photoinitiator composition. The monomer compositionpreferably includes a polyethylenic functional monomer. Preferably, thepolyethylenic functional monomer composition includes an aromaticcontaining polyether polyethylenic functional monomer. In oneembodiment, the polyethylenic functional monomer is preferably anethoxylated bisphenol A di(meth)acrylate.

[0038] The monomer composition may include additional monomers to modifythe properties of the formed eyeglass lens and/or the lens formingcomposition. Monomers which may be used in the monomer compositioninclude polyethylenic functional monomers containing groups selectedfrom acrylyl or methacrylyl.

[0039] In one embodiment, the photoinitiator composition preferablyincludes bis(2,6-dimethoxybenzoyl)-(2,4,4-trimethylphenyl)phosphineoxide, commercially available from Ciba Additives in Tarrytown, N.Y.under the trade name of Irgacure 819. In another embodiment, thephotoinitiator composition may include a mixture of photoinitiators.Preferably, a mixture of Irgacure 819 and 1-hydroxycyclohexylphenylketone, commercially available from Ciba Additives under the trade nameof Irgacure 184, is used.

[0040] In another embodiment, an ophthalmic eyeglass lens may be madefrom an activating light curable lens forming composition comprising amonomer composition, a photoinitiator composition and a co-initiatorcomposition. An activating light absorbing compound may also be present.An activating light absorbing compound is herein defined as a compoundwhich absorbs at least a portion of the activating light. The monomercomposition preferably includes a polyethylenic functional monomer.Preferably, the polyethylenic functional monomer is an aromaticcontaining polyether polyethylenic functional monomer. In oneembodiment, the polyethylenic functional monomer is preferably anethoxylated bisphenol A di(meth)acrylate.

[0041] The co-initiator composition preferably includes amineco-initiators. Preferably, acrylyl amines are included in theco-initiator composition. In one embodiment, the co-initiatorcomposition preferably includes a mixture of CN-384 and CN-386.

[0042] Examples of activating light absorbing compounds includesphotochromic compounds, UV stabilizers, UV absorbers, and/or dyes.

BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The above brief description as well as further objects, featuresand advantages of the methods and apparatus of the present inventionwill be more fully appreciated by reference to the following detaileddescription of presently preferred but nonetheless illustrativeembodiments in accordance with the present invention when taken inconjunction with the accompanying drawings in which:

[0044]FIG. 1 depicts a perspective view of a plastic lens formingapparatus.

[0045]FIG. 2 depicts a perspective view of a spin coating unit.

[0046]FIG. 3 depicts a cut-away side view of a spin coating unit.

[0047]FIG. 4 depicts a perspective view of a plastic lens formingapparatus with a portion of the body removed.

[0048]FIG. 5 depicts a perspective view of the components of a lenscuring unit

[0049]FIG. 6 depicts a perspective view of a plastic lens formingapparatus with a portion of the body removed and the coating unitsremoved.

[0050] FIGS. 7-10 depict various LCD filter patterns.

[0051]FIG. 11 depicts a mold assembly.

[0052]FIG. 12 depicts a post-cure unit.

[0053]FIG. 13 depicts a view of an embodiment of a heat source and aheat distributor.

[0054]FIG. 14 depicts a view of various embodiments of a heat source andheat distributors.

[0055]FIG. 15 depicts a view of an embodiment of a heat source and aheat distributor.

[0056]FIG. 16 depicts a view of an embodiment of two mold members and agasket.

[0057]FIG. 17 depicts a plot of the temperature of the lens formingcomposition versus time during the application of activating lightpulses.

[0058]FIG. 18 depicts a schematic diagram of a lens curing apparatuswith a light sensor and controller.

[0059]FIG. 19 depicts a view of an embodiment of a system simultaneouslyemploying both a flash light source and a continuous activating (e.g.,fluorescent) light source.

[0060]FIG. 20 depicts an embodiment of a system simultaneously employingtwo flash light sources.

[0061]FIG. 21 depicts an embodiment of a system employing an activatinglight controller.

[0062]FIG. 22 depicts a graph illustrating a temperature profile of acontinuous radiation cycle.

[0063]FIG. 23 depicts a graph illustrating temperature profiles for acontinuous irradiation cycle and a pulse irradiation cycle employed witha mold/gasket set having a 3.00D base curve, and while applying cooledair at 58° F. to the mold/gasket set.

[0064]FIG. 24 depicts a chart illustrating qualitative relationshipsamong curing cycle variables.

[0065]FIG. 25 depicts a graph illustrating temperature profiles for onecuring cycle for a mold/gasket set having a 6.00D base curve and usedwith three different light levels.

[0066]FIG. 26 depicts a graph illustrating continuous and pulsedtemperature profiles for a curing cycle employing a mold/gasket set witha 600D base curve.

[0067]FIG. 27 depicts a graph illustrating continuous and pulsedtemperature profiles for a curing cycle employing a mold/gasket set witha 4.50D base curve.

[0068]FIG. 28 depicts a graph illustrating continuous and pulsedtemperature profiles for a curing cycle employing a mold/gasket set witha 3.00D base curve.

[0069]FIG. 29 depicts a cross sectional view of a flat-top bifocal mold.

[0070]FIG. 30 depicts a plot of % transmittance of light versuswavelength for a photochromic lens.

[0071]FIG. 31 depicts a plot of % transmittance of light versuswavelength for both a colorless lens containing ultraviolet/visiblelight absorbers and a lens containing no ultraviolet/visible lightabsorbers.

[0072]FIG. 32 depicts an isometric view of an embodiment of a gasket.

[0073]FIG. 33 depicts a top view of the gasket of FIG. 1.

[0074]FIG. 34 depicts a cross-sectional view of an embodiment of amold/gasket assembly.

[0075]FIG. 35 depicts an isometric view of an embodiment of a gasket.

[0076]FIG. 36 depicts a top view of the gasket of FIG. 4.

[0077]FIG. 37 depicts a graph showing the absorption ranges of a varietyof photochromic compounds and light effectors.

[0078]FIG. 38 depicts a plastic lens forming apparatus which includestwo lens curing units.

[0079]FIG. 39 depicts chemical structure of acrylated amines.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0080] Apparatus, operating procedures, equipment, systems, methods, andcompositions for lens curing using activating light are availabe fromRapid Cast, Inc., Q2100, Inc., and Fast Cast, Inc. in Louisville, Ky.

[0081] Referring now to FIG. 1, a plastic lens curing apparatus isgenerally indicated by reference numeral 10. As shown in FIG. 1, lensforming apparatus 10 includes at least one coating unit 20, a lenscuring unit 30, a post-cure unit 40, and a controller 50. Preferably,apparatus 10 includes two coating units 20. Coating unit 20 ispreferably configured to apply a coating layer to a mold member or alens. Preferably, coating unit 20 is a spin coating unit. Lens curingunit 30 includes an activating light source for producing activatinglight. As used herein “activating light” means light that may affect achemical change. Activating light may include ultraviolet light (e.g.,light having a wavelength between about 300 nm to about 400 nm), actiniclight, visible light or infrared light. Generally, any wavelength oflight capable of affecting a chemical change may be classified asactivating. Chemical changes may be manifested in a number of forms. Achemical change may include, but is not limited to, any chemicalreaction that causes a polymerization to take place. Preferably thechemical change causes the formation of an initiator species within thelens forming composition, the initiator species being capable ofinitiating a chemical polymerization reaction. The activating lightsource is preferably configured to direct light toward a mold assembly.Post-cure unit 40 is preferably configured to complete thepolymerization of plastic lenses. Post-cure unit 40 preferably includesan activating light source and a heat source. Controller 50 ispreferably a programmable logic controller. Controller 50 is preferablycoupled to coating units 20, lens curing unit 30, and post-cure unit 40,such that the controller is capable of substantially simultaneouslyoperating the three units 20, 30, and 40. Controller 50 may be acomputer.

[0082] A coating unit for applying a coating composition to a lens or amold member and then curing the coating composition is described in U.S.Pat. No. 4,895,102 to Kachel et al., U.S. Pat. No. 3,494,326 to Upton,and U.S. Pat. No. 5,514,214 to Joel et al. (all of which areincorporated herein by reference). In addition, the apparatus shown inFIGS. 2 and 3 may also be used to apply coatings to lenses or moldmembers.

[0083]FIG. 2 depicts a pair of spin coating units 102 and 104. Thesespin coating units may be used to apply a scratch resistant coating or atint coating to a lens or mold member. Each of the coating unitsincludes an opening through which an operator may apply lenses and lensmold assemblies to a holder 108. Holder 108 is preferably partiallysurrounded by barrier 114. Barrier 114 is preferably coupled to a dish115. As shown in FIG. 3, the dish edges may be inclined to form aperipheral sidewall 121 that merges with barrier 114. The bottom 117 ofthe dish is preferably substantially flat. The flat bottom preferablyhas a circular opening that allows an elongated member 109 coupled tolens holder 108 to extend through the dish 115.

[0084] Holder 108 is preferably coupled to a motor 112 via elongatedmember 109. Motor 112 is preferably configured to cause rotation ofholder 108. In such a case, motor 112 is preferably configured to causerotation of elongated member 109, that in turn causes the rotation ofholder 108. The coating unit 102/104, may also include an electroniccontroller 140. Electronic controller 140 is preferably coupled to motor112 to control the rate at which holder 108 is rotated by motor 112.Electronic controller 140 may be coupled to a programmable logiccontroller, such as controller 50, shown in FIG. 1. The programmablelogic controller may send signals to the electronic controller tocontrol the rotational speed of holder 108. Preferably, motor 112 isconfigured to rotate holder 108 at different rates. Motor 112 ispreferably capable of rotating the lens or mold member at a rate of upto 1500 revolutions per minute (“RPM”).

[0085] In one embodiment, barrier 114 has an interior surface that maybe made or lined with an absorbent material such as foam rubber.Preferably, this absorbent material is disposable and removable. Theabsorbent material absorbs any liquids that fall off a lens or moldmember during use. Alternatively, the interior surface of barrier 114may be substantially non-absorbent, allowing any liquids used during thecoating process to move down barrier 114 into dish 115.

[0086] Coating units 20, are preferably positioned in a top portion 12of lens forming apparatus 10, as depicted in FIG. 1. A cover 22 ispreferably coupled to body 14 of the lens forming apparatus to allow topportion 12 to be covered during use. A light source 23 is preferablypositioned on an inner surface of cover 22. The light source includes atleast one lamp 24, preferably two or more lamps, positioned on the innersurface of cover 22. Lamps 24 may be positioned such that the lamps areoriented above the coating units 20 when cover 22 is closed. Lamps 24preferably emit activating light upon the lenses or mold memberspositioned within coating units 20. Lamps may have a variety of shapesincluding, but not limited to, linear (as depicted in FIG. 1), square,rectangular, circular, or oval. Activating light sources preferably emitlight having a wavelength that will initiate curing of various coatingmaterials. For example, most currently used coating materials arepreferably curable by activating light having wavelengths in theultraviolet region, therefore the light sources should exhibit strongultraviolet light emission. The light sources should, preferably,produce minimal heat during use. Thus, lamps 24 will preferably have lowheat output. Lamps that exhibit strong ultraviolet light emission have apeak output at a wavelength in the ultraviolet light region, betweenabout 200 nm to about 400 nm, preferably the peak output is betweenabout 200 nm to 300 nm, and more preferably at about 254 nm. In oneembodiment, lamps 24 may be lamps that have a peak output in theultraviolet light region, and have relatively low heat output. Suchlights are commonly known as “germicidal” lights and any such light maybe used. A “germicidal” light emitting light with a peak output in thedesired ultraviolet region is commercially available from Voltarc, Inc.of Fairfield, Conn. as model UV-WX G10T5.

[0087] An advantage of using a spin coating unit is that lamps of avariety of shapes may be used (e.g., linear lamps) for the curing of thecoating materials. In one embodiment, a coating material is preferablycured in a substantially uniform manner to ensure that the coating isformed uniformly on the mold member or lens. With a spin coating unit,the object to be coated may be spun at speeds high enough to ensure thata substantially uniform distribution of light reaches the object duringthe curing process, regardless of the shape of the light source. The useof a spin coating unit preferably allows the use of commerciallyavailable linear light sources for the curing of coating materials.

[0088] A switch may be incorporated into cover 22. The switch ispreferably electrically coupled to light source 23 such that the switchmust be activated prior to turning the light source on. Preferably, theswitch is positioned such that closing the cover causes the switch tobecome activated. In this manner, the lights will preferably remain offuntil the cover is closed, thus preventing inadvertent exposure of anoperator to the light from light source 23.

[0089] During use a lens or lens mold assembly may be placed on the lensholder 108. The lens holder 108 may include a suction cup connected to ametal bar. The concave surface of the suction cup may be attachable to aface of a mold or lens, and the convex surface of the suction cup may beattached to a metal bar. The metal bar may be coupled to motor 112. Thelens holder may also include movable arms and a spring assembly that maybe together operable to hold a lens against the lens holder with springtension during use.

[0090] As shown in FIG. 4, the curing unit 30 may include an upper lightsource 214, a lens drawer assembly 216, and a lower light source 218.Lens drawer assembly 216 preferably includes a mold assembly holder 220,more preferably at least two mold assembly holders 220. Each of the moldassembly holders 220 is preferably configured to hold a pair of moldmembers that together with a gasket form a mold assembly. The lensdrawer assembly 216 is preferably slidingly mounted on a guide. Duringuse, mold assemblies may be placed in the mold assembly holders 220while the lens drawer assembly is in the open position (i.e., when thedoor extends from the front of the lens curing unit). After the moldassemblies have been loaded into the mold holder 220 the door may beslid into a closed position, with the mold assemblies directly under theupper light source 214 and above the lower light source 218. Vents (notshown) may be placed in communication with the lens curing unit to allowa stream of air to be directed toward the mold members when the moldmembers are positioned beneath the upper lamps. An exhaust fan (notshown) may communicate with the vents to improve the circulation of airflowing through the lens curing unit.

[0091] As shown in FIGS. 4 and 5, it is preferred that the upper lightsource 214 and lower light source 216 include a plurality of activatinglight generating devices or lamps 240. Preferably, the lamps areoriented proximate each other to form a row of lights, as depicted inFIG. 4. Preferably, three or four lamps are positioned to providesubstantially uniform radiation over the entire surface of the moldassembly to be cured. The lamps 240, preferably generate activatinglight. Lamps 240 may be supported by and electrically connected tosuitable fixtures 242. Lamps 240 may generate either ultraviolet light,actinic light, visible light, and/or infrared light. The choice of lampsis preferably based on the monomers used in the lens formingcomposition. In one embodiment, the activating light may be generatedfrom a fluorescent lamp. The fluorescent lamp preferably has a strongemission spectra in the 380 to 490 nm region. A fluorescent lampemitting activating light with the described wavelengths is commerciallyavailable from Philips as model TLD-15W/03. In another embodiment, thelamps may be ultraviolet lights.

[0092] In one embodiment, the activating light sources may be turned onand off quickly between exposures. Flasher ballasts 250, depicted inFIG. 6, may be used for this function. The flasher ballast may bepositioned beneath the coating unit. A flasher ballast 250 may operatein a standby mode wherein a low current is supplied to the lampfilaments to keep the filaments warm and thereby reduce the strike timeof the lamp. Such a ballast is commercially available from Magnatek, Incof Bridgeport, Conn. Power supply 252 may also be located proximate theflasher ballasts, underneath the coating unit.

[0093]FIG. 18 schematically depicts a light control system. The lightsources 214 in lens curing unit 30 apply light towards the mold assembly352. A light sensor 700 may be located adjacent the light sources 214.Preferably, the light sensor 700 is a photoresistor light sensor(photodiodes or other light sensors may also be usable in thisapplication). The light sensor 700 with a filter 750 may be connected tolamp driver 702 via wires 704. Lamp driver 702 sends a current throughthe light sensor 700 and receives a return signal from the light sensor700. The return signal may be compared against an adjustable set point,and then the electrical frequency sent to the light sources 214 viawires 706 may be varied depending on the differences between the setpoint and the signal received from the light sensor 700. Preferably, thelight output is maintained within about +/−1.0 percent.

[0094] One “lamp driver” or light controller is a Mercron Model FX0696-4and Model FX06120-6 (Mercron, Inc., Dallas, Tex., U.S.A.). These lightcontrollers are described in U.S. Pat. Nos. 4,717,863 and 4,937,470.

[0095] In an embodiment, a flash lamp emits activating light pulses tocure the lens forming material. It is believed that a flash lamp wouldprovide a smaller, cooler, less expensive, and more reliable lightsource than other sources. The power supply for a flash lamp tends todraw relatively minimal current while charging its capacitor bank. Theflash lamp discharges the stored energy on a microsecond scale toproduce very high peak intensities from the flash tube itself. Thusflash lamps tend to require less power for operation and generate lessheat than other light sources used for activating light curing. A flashlamp may also be used to cure a lens coating.

[0096] In an embodiment, the flash lamp used to direct activating lighttoward at least one of the mold members is a xenon light source. Thelens coating may also be cured using a xenon light source. Referring toFIG. 21, xenon light source 980 preferably contains photostrobe 992having a tube 996 and electrodes to allow the transmission of activatinglight. The tube may include borosilicate glass or quartz. A quartz tubewill generally withstand about 3 to 10 times more power than a hardglass tube. The tube may be in the shape of a ring, U, helix, or it maybe linear. The tube may include capacitive trigger electrode 995. Thecapacitive trigger electrode may include a wire, silver strip, orconductive coating located on the exterior of tube 996. The xenon lightsource is preferably adapted to deliver pulses of light for a durationof less than about 1 second, more preferably between about {fraction(1/10)} of a second and about {fraction (1/1000)} of a second, and morepreferably still between about {fraction (1/400)} of a second and{fraction (1/600)} of a second. The xenon source may be adapted todeliver light pulses about every 4 seconds or less. The relatively highintensity of the xenon lamp and short pulse duration may allow rapidcuring of the lens forming composition without imparting significantradiative heat to the composition.

[0097] In an embodiment, controller 990 (shown in FIG. 21) controls theintensity and duration of activating light pulses delivered fromactivating light source 980 and the time interval between pulses, shownin FIG. 19. Activating light source 980 may include capacitor 994, thatstores the energy required to deliver the pulses of activating light.Capacitor 994 may be adapted to allow pulses of activating light to bedelivered as frequently as desired. Temperature monitor 997 may belocated at a number of positions within mold chamber 984. Thetemperature monitor may measure the temperature within the chamberand/or the temperature of air exiting the chamber. The system may beconfigured to send a signal to cooler 988 and/or distributor 986 (shownin FIG. 19) to vary the amount and/or temperature of the cooling air.The temperature monitor may also determine the temperature at any of anumber of locations proximate the mold cavity and send a signal tocontroller 990 to vary the pulse duration, pulse intensity, or timebetween pulses as a function of a temperature within mold chamber 984.

[0098] In an embodiment, light sensor 999 may be used to determine theintensity of activating light emanating from source 980. The lightsensor is preferably configured to send a signal to controller 990, thatis preferably configured to maintain the intensity of the activatinglight at a selected level. Filter 998 may be positioned betweenactivating light source 980 and light sensor 999 and is preferablyconfigured to inhibit non-activating light rays from contacting lightsensor 999, while allowing activating rays to contact the sensor. In oneembodiment, the filter may include 365 N glass or any other materialadapted to filter non-activating light (e.g., visible light) andtransmit activating light.

[0099] In an embodiment, more than one activating light source may beused to simultaneously apply activating pulses to the lens formingcomposition. Such an embodiment is shown in FIG. 20. Activating lightsources 980 a and 980 b may be positioned around mold chamber 985 sothat pulses may be directed toward the front face of a lens and the backface of a lens substantially simultaneously. Mold chamber 985 ispreferably adapted to hold a mold in a vertical position such thatpulses from activating light source 980 a may be applied to the face ofa first mold member, while pulses from activating light source 980 b maybe applied to the face of a second mold member. In an embodiment,activating light source 980 b applies activating light pulses to a backsurface of a lens more frequently than xenon source 980 a appliesactivating light pulses to a front surface of a lens. Activating lightsources 980 a and 980 b may be configured such that one source applieslight to mold chamber 984 from a position above the chamber while theother activating light source applies light to the mold chamber from aposition below the chamber.

[0100] In an embodiment, a xenon light source and a relatively lowintensity (e.g., fluorescent) light source may be used to simultaneouslyapply activating light to a mold chamber. As illustrated in FIG. 19,xenon source 980 may apply activating light to one side of mold chamber984 while low intensity fluorescent source 982 applies activating lightto another side of the mold chamber. Fluorescent source 982 may includea compact fluorescent “light bucket” or a diffused fluorescent lamp. Thefluorescent light source may deliver continuous or substantially pulsedactivating light as the xenon source delivers activating light pulses.The fluorescent source may deliver continuous activating light rayshaving a relatively low intensity of less than about 100 microwatts/cm².

[0101] In one embodiment, an upper light filter 254 may be positionedbetween upper light source 214 and lens drawer assembly 216, as depictedin FIG. 5. A lower light filter 256 may be positioned between lowerlight source 218 and lens drawer assembly 216. The upper light filter254 and lower light filter 256 are shown in FIG. 5 as being made of asingle filter member, however, those of ordinary skill in the art willrecognize that each of the filters may include two or more filtermembers. The components of upper light filter 254 and lower light filter256 are preferably modified depending upon the characteristics of thelens to be molded. For instance, in an embodiment for making negativelenses, the upper light filter 254 includes a plate of Pyrex glass thatmay be frosted on both sides resting upon a plate of clear Pyrex glass.The lower light filter 256 includes a plate of Pyrex glass, frosted onone side, resting upon a plate of clear Pyrex glass with a device forreducing the intensity of activating light incident upon the centerportion relative to the edge portion of the mold assembly.

[0102] Conversely, in a preferred arrangement for producing positivelenses, the upper light filter 254 includes a plate of Pyrex glassfrosted on one or both sides and a plate of clear Pyrex glass restingupon the plate of frosted Pyrex glass with a device for reducing theintensity of activating light incident upon the edge portion in relationto the center portion of the mold assembly. The lower light filter 256includes a plate of clear Pyrex glass frosted on one side resting upon aplate of clear Pyrex glass with a device for reducing the intensity ofactivating light incident upon the edge portion in relation to thecenter portion of the mold assembly. In this arrangement, in place of adevice for reducing the relative intensity of activating light incidentupon the edge portion of the lens, the diameter of the aperture 250 maybe reduced to achieve the same result, i.e., to reduce the relativeintensity of activating light incident upon the edge portion of the moldassembly.

[0103] It should be apparent to those skilled in the art that eachfilter 254 or 256 could be composed of a plurality of filter members orinclude any other means or device effective to reduce the light to itsdesired intensity, to diffuse the light and/or to create a lightintensity gradient across the mold assemblies. Alternately, in certainembodiments no filter elements may be used.

[0104] In one embodiment, upper light filter 254 or lower light filter256 each include at least one plate of Pyrex glass having at least onefrosted surface. Also, either or both of the filters may include morethan one plate of Pyrex glass each frosted on one or both surfaces,and/or one or more sheets of tracing paper. After passing throughfrosted Pyrex glass, the activating light is believed to have no sharpintensity discontinuities. By removing the sharp intensity distributionsa reduction in optical distortions in the finished lens may be achieved.Those of ordinary skill in the art will recognize that other means maybe used to diffuse the activating light so that it has no sharpintensity discontinuities.

[0105] In another embodiment, upper light filter 254 and lower lightfilter 256 may be liquid crystal display (“LCD”) panels. Preferably, theLCD panel is a monochrome trans-flective panel with the back light andreflector removed. A monochrome trans-flective LCD panel is manufacturedby Sharp Corporation and may be purchased from Earth Computer Products.The LCD panels are preferably positioned such that light from the lightsources passes through the LCD panels to the lens drawer assembly 216.The intensity of the light is preferably reduced as the light passesthrough the LCD panel. The LCD panel is preferably programmable suchthat the light transmissibility of the LCD panel may be altered. In use,a predetermined pattern of light and dark regions may be displayed onthe LCD panel. As light from the light sources hits these regions thelight may be transmitted through the light regions with a higherintensity than through the darker regions. In this manner, the patternof light and dark areas on the LCD panel may be manipulated such thatlight having the optimal curing intensity pattern hits the moldassemblies. Although the LCD panel is not entirely opaque in itsblackened out state, it may still reduce the intensity of light reachingthe mold assemblies. Typically, the light transmission ratio between thelightest and darkest regions of the LCD panel is about 4 to 1.

[0106] The use of an LCD panel as a light filter offers a number ofadvantages over the conventional filter systems described earlier. Oneadvantage is that the filter pattern may be changed actively during acuring cycle. For example, the pattern of light and dark regions may bemanipulated such that a lens is initially cured from the center of thelens then the curing may be gradually expanded to the outer edges of thelens. This type of curing pattern may allow a more uniformly cured lensto be formed. In some instances, curing in this manner may also be usedto alter the final power of the formed lens.

[0107] Another advantage is that the LCD panel may be used as a partialshutter to reduce the intensity of light reaching the mold assembly. Byblackening the entire LCD panel the amount of light reaching any portionof the mold assembly may be reduced. In this manner, the LCD may be usedto create “pulses” of light by alternating between a transmissive anddarkened mode. By having the LCD panel create these light “pulses” aflash ballast or similar pulse generating equipment may be unnecessary.Thus, the light sources may remain on during the entire curing cycle,with the LCD panel creating the curing light pulses. This may alsoincrease the lifetime of the lamps, since the rapid cycling of lampstends to reduce the lamps' lifetime.

[0108] In another embodiment, an LCD panel may be used to allowdifferent patterns and/or intensities of light to reach two separatemold assemblies. As depicted in FIG. 4, the lens curing unit may beconfigured to substantially simultaneously irradiate two moldassemblies. If the mold assemblies are being used to create lenseshaving the same power the light irradiation pattern and/or intensity maybe substantially the same for each mold assembly. If the mold assembliesare being used to create lenses having significantly different powers,each mold assembly may require a significantly different lightirradiation pattern and/or intensity. The use of an LCD filter may allowthe irradiation of each of the mold assemblies to be controlledindividually. For example, a first mold assembly may require a pulsedcuring scheme, while the other mold assembly may require a continuousirradiation pattern through a patterned filter. The use of an LCD panelmay allow such lenses to be formed substantially simultaneously. A firstportion of the LCD panel between the light source and the first moldingapparatus may be alternatively switched between a darkened and anundarkened state. While a first portion is used to create pulses ofactivating light, another portion of the LCD panel may be formed intothe specific pattern required for the continuous curing of the otherlens.

[0109] When non-LCD type filters are used it may be necessary tomaintain a library of filters for use in the production of differenttypes of prescription lenses. Typically, each individual prescriptionwill need a particular filter pattern to obtain a high quality lens.Since an LCD panel may be programmed into a variety of patterns, it maybe possible to rely on a single LCD panel, rather than a library offilters. The LCD panel may be programmed to fit the needs of thespecific type of lens being formed. Such a system also minimizes theneed for human intervention, since a controller may be programmed for adesired pattern, rather than the operator having to choose among a“library” of filters.

[0110] The control of the temperature of an LCD panel filter during acuring cycle may be important for achieving a proper lens. In general asthe temperature of a panel is increased the lighter regions of the panelmay become darker (i.e., less light transmissive). Thus, it may benecessary to control the temperature of the LCD panel during curing toensure that light having the appropriate intensity reaches the moldassemblies. A cooling system or heating system may therefore, be coupledto the LCD panel to ensure proper temperature control. In oneembodiment, it is preferred that a substantially transparent heater isattached to the LCD panel. By increasing the temperature of the LCDpanel the light transmissibility of the panel may be decreased. It ispreferred that an LCD panel be maintained above room temperature sinceat room temperature the panel may be too light to sufficiently inhibitthe light from reaching the mold assemblies. In order to obtain a properpattern of light and dark regions when the LCD panel is heated it may benecessary to adjust the contrast of the panel. This adjustment may bedone either manually or electronically.

[0111] The LCD panel filters may be coupled to a programmable logicdevice that may be used to design and store patterns for use duringcuring. FIG. 7-10 show a number of patterns which may be generated on anLCD panel and used to filter activating light. Each of these patterns ispreferably used for the production of a lens having a specificprescription power.

[0112] As shown in FIG. 11, the mold assembly 352 may include opposedmold members 378, separated by an annular gasket 380 to define a lensmolding cavity 382. The opposed mold members 378 and the annular gasket380 may be shaped and selected in a manner to produce a lens having adesired diopter.

[0113] The mold members 378 may be formed of any suitable material thatwill permit the passage of activating light. The mold members 378 arepreferably formed of glass. Each mold member 378 has an outer peripheralsurface 384 and a pair of opposed surfaces 386 and 388 with the surfaces386 and 388 being precision ground. Preferably the mold members 378 havedesirable activating light transmission characteristics and both thecasting surface 386 and non-casting surface 388 preferably have nosurface aberrations, waves, scratches or other defects as these may bereproduced in the finished lens.

[0114] As noted above, the mold members 378 are preferably adapted to beheld in spaced apart relation to define a lens molding cavity 382between the facing surfaces 386 thereof. The mold members 378 arepreferably held in a spaced apart relation by a T-shaped flexibleannular gasket 380 that seals the lens molding cavity 382 from theexterior of the mold members 378. In use, the gasket 380 may besupported on a portion of the mold assembly holder 220 (shown in FIG.4).

[0115] In this manner, the upper or back mold member 390 has a convexinner surface 386 while the lower or front mold member 392 has a concaveinner surface 386 so that the resulting lens molding cavity 382 ispreferably shaped to form a lens with a desired configuration. Thus, byselecting the mold members 378 with a desired surface 386, lenses withdifferent characteristics, such as focal lengths, may be produced.

[0116] Rays of activating light emanating from lamps 240 preferably passthrough the mold members 378 and act on a lens forming material disposedin the mold cavity 382 in a manner discussed below so as to form a lens.As noted above, the rays of activating light may pass through a suitablefilter 254 or 256 before impinging upon the mold assembly 352.

[0117] The mold members 378, preferably, are formed from a material thatwill not transmit activating light having a wavelength belowapproximately 300 nm. Suitable materials are Schott Crown, S-1 or S-3glass manufactured and sold by Schott Optical Glass Inc., of Duryea, Pa.or Corning 8092 glass sold by Corning Glass of Corning, New York. Asource of flat-top or single vision molds may be Augen Lens Co. in SanDiego, Calif.

[0118] The annular gasket 380 maybe formed of vinyl material thatexhibits good lip finish and maintains sufficient flexibility atconditions throughout the lens curing process. In an embodiment, theannular gasket 380 is formed of silicone rubber material such as GESE6035 which is commercially available from General Electric. In anotherpreferred embodiment, the annular gasket 380 is formed of copolymers ofethylene and vinyl acetate which are commercially available from E. I.DuPont de Nemours & Co. under the trade name ELVAX7. Preferred ELVAX7resins are ELVAX7 350 having a melt index of 17.3-20.9 dg/min and avinyl acetate content of 24.3-25.7 wt. %, ELVAX7 250 having a melt indexof 22.0-28.0 dg/min and a vinyl acetate content of 27.2-28.8 wt. %,ELVAX7 240 having a melt index of 38.0-48.0 dg/min and a vinyl acetatecontent of 27.2-28.8 wt. %, and ELVAX7 150 having a melt index of38.0-48.0 dg/min and a vinyl acetate content of 32.0-34.0 wt. %. Inanother embodiment, the gasket may be made from polyethylene. Regardlessof the particular material, the gaskets 80 may be prepared byconventional injection molding or compression molding techniques whichare well-known by those of ordinary skill in the art.

[0119] In another embodiment, FIGS. 32 and 33 present an isometric viewand a top view, respectively, of a gasket 510. Gasket 510 may beannular, and is preferably configured to engage a mold set for forming amold assembly. Gasket 510 is preferably characterized by at least fourdiscrete projections 511. Gasket 510 preferably has an exterior surface514 and an interior surface 512. The projections 511 are preferablyarranged upon inner surface 512 such that they are substantiallycoplanar. The projections are preferably evenly spaced around theinterior surface of the gasket Preferably, the spacing along theinterior surface of the gasket between each projection is about 90degrees. Although four projections are preferred, it is envisioned thatmore than four could be incorporated. The gasket 510 may be formed of asilicone rubber material such as GE SE6035 which is commerciallyavailable from General Electric. In another embodiment, the gasket 510may be formed of copolymers of ethylene and vinyl acetate which arecommercially available from E. I. DuPont de Nemours & Co. under thetrade name ELVAX7. In another embodiment, the gasket 510 may be formedfrom polyethylene.

[0120] As shown in FIG. 34, projections 511 are preferably capable ofspacing mold members 526 of a mold set. Mold members 526 may be any ofthe various types and sizes of mold members that are well known in theart. A mold cavity 528 at least partially defined by mold members 526and gasket 510, is preferably capable of retaining a lens formingcomposition. Preferably, the seal between gasket 510 and mold members526 is as complete as possible. The height of each projection 511preferably controls the spacing between mold members 526, and thus thethickness of the finished lens. By selecting proper gaskets and moldsets, lens cavities may be created to produce lenses of various powers.

[0121] A mold assembly consists of two mold members. A front mold member526 a and a back mold member 526 b, as depicted in FIG. 34. The backmold member is also known as the convex mold member. The back moldmember preferably defines the concave surface of a convex lens.Referring back to FIGS. 32 and 33, locations where the steep axis 522and the flat axis 524 of the back mold member 526 b preferably lie inrelation to gasket 510 have been indicated. In conventional gaskets, araised lip may be used to space mold members. The thickness of this lipvaries over the circumference of the lip in a manner appropriate withthe type of mold set a particular gasket is designed to be used with. Inorder to have the flexibility to use a certain number of molds, anequivalent amount of conventional gaskets is typically kept in stock.

[0122] However, within a class of mold sets there may be points alongthe outer curvature of a the back mold member where each member of aclass of back mold members is shaped similarly. These points may befound at locations along gasket 510, oblique to the steep and flat axesof the mold members. In a preferred embodiment, these points are atabout 45 degree angles to the steep and flat axes of the mold members.By using discrete projections 511 to space the mold members at thesepoints, an individual gasket could be used with a variety of mold sets.Therefore, the number of gaskets that would have to be kept in stock maybe greatly reduced.

[0123] In addition, gasket 510 may include a recession 518 for receivinga lens forming composition. Lip 520 may be pulled back in order to allowa lens forming composition to be introduced into the cavity. Vent ports516 may be incorporated to facilitate the escape of air from the moldcavity as a lens forming composition is introduced.

[0124] A method for making a plastic eyeglass lenses using gasket 510 ispresented. The method preferably includes engaging gasket 510 with afirst mold set for forming a first lens of a first power. The first moldset preferably contains at least a front mold member 526 a and a backmold member 526 b. A mold cavity for retaining a lens formingcomposition may be at least partially defined by mold members 526 a and526 b and gasket 510. Gasket 510 is preferably characterized by at leastfour discrete projections 511 arranged on interior surface 512 forspacing the mold members. Engaging gasket 510 with the mold setpreferably includes positioning the mold members such that each of theprojections 511 forms an oblique angle with the steep and flat axis ofthe back mold member 526 b. In a preferred embodiment, this angle isabout 45 degrees. The method preferably further includes introducing alens forming composition into mold cavity 528 and curing the lensforming composition. Curing may include exposing the composition toactivating light and/or thermal radiation. After the lens is cured, thefirst mold set may be removed from the gasket and the gasket may then beengaged with a second mold set for forming a second lens of a secondpower.

[0125]FIGS. 35 and 36 present an isometric view and a top view,respectively, of an improved gasket. Gasket 530 may be composed ofsimilar materials as gasket 510. Like gasket 510, gasket 530 ispreferably annular, but may be take a variety of shapes. In addition,gasket 530 may incorporate projections 531 in a manner similar to theprojections 511 shown in FIG. 32. Alternatively, gasket 530 may includea raised lip along interior surface 532 or another method of spacingmold members that is conventional in the art.

[0126] Gasket 530 preferably includes a fill port 538 for receiving alens forming composition while gasket 530 is fully engaged to a moldset. Fill port 538 preferably extends from interior surface 532 ofgasket 530 to an exterior surface 534 of gasket 530. Consequently,gasket 530 need not be partially disengaged from a mold member of a moldset in order to receive a lens forming composition. In order tointroduce a lens forming composition into the mold cavity defined by aconventional mold/gasket assembly the gasket must be at least partiallydisengaged from the mold members. During the process of filling the moldcavity, lens forming composition may drip onto the backside of a moldmember. Lens forming composition on the backside of a mold member maycause activating light used to cure the lens to become locally focused,and may cause optical distortions in the final product. Because fillport 538 allows lens forming composition to be introduced into a moldcavity while gasket 530 is fully engaged to a mold set, gasket 530preferably avoids this problem. In addition, fill port 538 may be ofsufficient size to allow air to escape during the introduction of a lensforming composition into a mold cavity; however, gasket 530 may alsoincorporate vent ports 536 to facilitate the escape of air.

[0127] A method for making a plastic eyeglass lens using gasket 530preferably includes engaging gasket 530 with a first mold set forforming a first lens of a first power. The first mold set preferablycontains at least a front mold member and a back mold member. A moldcavity for retaining a lens forming composition may be at leastpartially defined by the front mold member, the back mold member, andthe gasket Preferably, the method further includes introducing a lensforming composition through fill port 538, wherein the first and secondmold members remain fully engaged with the gasket during theintroduction of the lens forming composition. The lens formingcomposition may then be cured by use of activating light and/or thermalradiation.

[0128] In operation, the apparatus may be appropriately configured forthe production of positive lenses which are relatively thick at thecenter or negative lenses which are relatively thick at the edge. Toreduce the likelihood of premature release, the relatively thickportions of a lens are preferably polymerized at a faster rate than therelatively thin portions of a lens.

[0129] The rate of polymerization taking place at various portions of alens may be controlled by varying the relative intensity of activatinglight incident upon particular portions of a lens. The rate ofpolymerization taking place at various portions of a lens may also becontrolled by directing air across the mold members 378 to cool the moldassembly 352.

[0130] For positive lenses, the intensity of incident activating lightis preferably reduced at the edge portion of the lens so that thethicker center portion of the lens polymerizes faster than the thinneredge portion of the lens. Conversely, for a negative lens, the intensityof incident activating light is preferably reduced at the center portionof the lens so that the thicker edge portion of the lens polymerizesfaster than the thinner center portion of the lens. For either apositive lens or a negative lens, air may be directed across the facesof the mold members 378 to cool the mold assembly 352. As the overallintensity of incident activating light is increased, more cooling isneeded which may be accomplished by either or both of increasing thevelocity of the air and reducing the temperature of the air.

[0131] It is well known by those of ordinary skill in the art that lensforming materials tend to shrink as they cure. If the relatively thinportion of a lens is allowed to polymerize before the relatively thickportion, the relatively thin portion will tend to be rigid at the timethe relatively thick portion cures and shrinks and the lens will eitherrelease prematurely from or crack the mold members. Accordingly, whenthe relative intensity of activating light incident upon the edgeportion of a positive lens is reduced relative to the center portion,the center portion may polymerize faster and shrink before the edgeportion is rigid so that the shrinkage is more uniform. Conversely, whenthe relative intensity of activating light incident upon the centerportion of a negative lens is reduced relative to the edge portion, theedge portion may polymerize faster and shrink before the center becomesrigid so that the shrinkage is more uniform.

[0132] The variation of the relative intensity of activating lightincident upon a lens may be accomplished in a variety of ways. Accordingto one method, in the case of a positive lens, a ring of opaque materialmay be placed between the lamps and the mold assembly so that theincident activating light falls mainly on the thicker center portion ofthe lens. Alternatively, when an LCD panel is used as the filter, thepanel may be programmed to form a pattern so that the incidentactivating light falls mainly on the thicker center portion of the lens(See FIG. 7, patterns A, B, C, D, F, H and I). Conversely, for anegative lens, a disk of opaque material may be placed between the lamps240 and the mold assembly 352 so that the incident activating lightfalls mainly on the edge portion of the lens. Alternatively, when an LCDpanel is used as the filter, the panel may be programmed to form apattern so that the incident activating light falls mainly on thethicker edge portion of the lens (See FIG. 9, patterns C, F, I, and FIG.10, patterns A, B, D, E, G, and H).

[0133] According to another method, in the case of a negative lens, asheet material or an LCD panel having a pattern with a variable degreeof opacity ranging from opaque at a central portion to transparent at aradial outer portion may be disposed between the lamps 240 and the moldassembly 352. Conversely, for a positive lens, a sheet material or LCDpanel having a pattern with a variable degree of opacity ranging fromtransparent at a central portion to opaque at a radial outer portion maybe disposed between the lamps 240 and the mold assembly 352.

[0134] As noted above, the mold assembly 352 may be cooled during curingof the lens forming material as the overall intensity of the incidentactivating light is increased. Cooling of the mold assembly 352generally reduces the likelihood of premature release by slowing thereaction and improving adhesion. There may also be improvements in theoptical quality, stress characteristics and impact resistance of thelens. Cooling of the mold assembly 352 is preferably accomplished byblowing air across the mold assembly 352. The air preferably has atemperature ranging between 15 and 85° F. (about −9.4° C. to 29.4° C.)to allow for a curing time of between 30 and 10 minutes. The airdistribution devices have been found to be particularly advantageous asthey may be specifically designed to direct air directly across thesurface of the opposed mold members 378. After passing across thesurface of the opposed mold members 378, the air emanating from the airdistribution devices may be vented out of the system. Alternately theair emanating from the air distribution devices may be recycled back toan air cooler. In another embodiment, the mold assembly 352 may also becooled by disposing the mold assembly in a liquid cooling bath.

[0135] The opposed mold members 378 are preferably thoroughly cleanedbetween each curing run as any dirt or other impurity on the moldmembers 378 may cause premature release. The mold members 378 may becleaned by any conventional means well known to those of ordinary skillin the art such as with a domestic cleaning product, i.e., Mr. Clean™available from Proctor and Gamble. Those of ordinary skill in the artwill recognize, however, that many other techniques may also be used forcleaning the mold members 378.

[0136] After curing of the lens in lens curing unit 30, the lens may bede-molded and post-cured in the post-cure unit 40. Post-cure unit 40 ispreferably configured to apply light, heat or a combination of light andheat to the lens. As shown in FIG. 12, post-cure unit 40 may include alight source 414, a lens drawer assembly 416, and a heat source 418.Lens drawer assembly 416 preferably includes a lens holder 420, morepreferably at least two lens holders 420. Lens drawer assembly 416 ispreferably slidingly mounted on a guide. Preferably, lens drawerassembly 416 is made from a ceramic material. Cured lenses may be placedin lens holders 420 while the lens drawer assembly 416 is in the openposition (i.e., when the door extends from the front of post-cure unit40). After the lenses have been loaded into lens holders 420 the doormay be slid into a closed position, with the lenses directly under lightsource 414 and above heat source 418.

[0137] As shown in FIG. 12, it is preferred that the light source 414includes a plurality of light generating devices or lamps 440.Preferably, lamps 440 may be oriented above each of the lens holderswhen the lens drawer assembly is closed. The lamps 440, preferably,generate activating light. The lamps 440 may be supported by andelectrically connected to suitable fixtures 442. The fixtures may be atleast partially reflective and concave in shape to direct light from thelamps 440 toward the lens holders. The lamps may generate eitherultraviolet light, actinic light, visible light, and/or infrared light.The choice of lamps is preferably based on the monomers used in the lensforming composition. In one embodiment, the activating light may begenerated from a fluorescent lamp. The fluorescent lamp preferably has astrong emission spectra from about 200 nm to about 800 nm, morepreferably between about 200 nm to about 400 nm. A fluorescent lampemitting activating light with the described wavelengths is commerciallyavailable from Phillips as model PL-S 9W/10. In another embodiment, thelamp may generate ultraviolet light.

[0138] In one embodiment, the activating light source may be turned onand off quickly between exposures. A flasher ballast may be used forthis function. The flasher ballast may be positioned beneath thepost-cure unit. A flasher ballast may operate in a standby mode whereina low current is preferably supplied to the lamp filaments to keep thefilaments warm and thereby reduce the strike time of the lamp. Such aballast is commercially available from Magnatek, Inc of Bridgeport,Conn.

[0139] Heat source 418 may be configured to heat the interior of thepost-cure unit Preferably, heat source 418 is a resistive heater. Heatsource 418 may be made up of one or two resistive heaters. Thetemperature of heat source 418 may be thermostatically controlled. Byheating the interior of the post-cure unit the lenses which are placedin post-cure unit 40 may be heated to complete curing of the lensforming material. Post-cure unit 40 may also include a fan to circulateair within the unit. The circulation of air within the unit may helpmaintain a relatively uniform temperature within the unit. The fan mayalso be used to cool the temperature of post-cure unit 40 aftercompletion of the post cure process.

[0140] In an embodiment, described as follows, a lens cured by exposureto activating light may be further processed by conductive heating. Suchconductive heating tends to enhance the degree of cross-linking in thelens and to increase the tintability of the lens. A lens formingmaterial is preferably placed in mold cavity 900 (illustrated in FIG.16), which is defined by at least first mold member 902 and second moldmember 904. Activating light is directed toward at least one of the moldmembers, thereby curing the lens forming material to a lens. Heatdistributor 910 (shown in FIG. 13) may be adapted to distributeconductive heat from conductive heat source 418 to at least one moldmember. Heat distributor 910 is preferably flexible such that at least aportion of it may be shaped to substantially conform to the shape offace 906 or face 907 of first mold member 902 or second mold member 904,respectively. Heat distributor 910 is preferably placed in contact withconductive heat source 418, and mold member 902 is preferably placed onheat distributor 910 such that face 906 of the mold member rests on topof the heat distributor 910. Heat distributor 910 may be coupled to heatsource 418. Heat is preferably conductively applied to the heatdistributor 910 by the heat source 418. Heat is preferably conductedfrom the heat distributor 910 through the mold member to a face of thelens. The heat distributor may be shaped to accommodate face 906 offirst mold member 902 or face 907 of second mold member 904 such thatthe heat is applied to front face 916 or back face 915 of the lens. Thetemperature of heat source 418 may be thermostatically controlled.

[0141] In an embodiment, a resistive heater 418 (shown in FIG. 17) maybe used as a heat source to provide conductive heat to the lens. Anumber of other heat sources may be used. In an embodiment, heatdistributor 910 may include countershape 920. Countershape 920 may beplaced on top of the hot plate to distribute conductive heat from thehot plate. The countershape is preferably flexible such that at least aportion of it may substantially conform to the shape of an outside faceof a mold member. The countershape may be hemispherical and eitherconvex or concave depending upon whether the surface of the moldassembly to be placed upon it is convex or concave. For example, whenthe concave surface of the back mold is utilized to conduct heat intothe lens assembly, a convex countershape is preferably provided to restthe assembly on.

[0142] Countershape 920 may include a glass mold, a metal optical lap, apile of hot salt and/or sand, or any of a number of other devicesadapted to conduct heat from heat source 912. It should be understoodthat FIG. 17 includes combinations of a number of embodiments forillustrative purposes. Any number of identical or distinct countershapesmay be used in combination on top of a heat source. In an embodiment, acountershape includes a container 922 filled with particles 924. Theparticles preferably include metal or ceramic material. Countershape 920may include heat distributor 910. A layer 914 of material may be placedover the countershape 920 or heat distributor 910 to provide slow,smooth, uniform heat conduction into the lens mold assembly. This layerpreferably has a relatively low heat conductivity and may be made ofrubber, cloth, Nomex™ fabric or any other suitable material thatprovides slow, smooth, uniform conduction.

[0143] In an embodiment, countershape 920 includes layer 914 (e.g., abag or container) filled with particles 924 such that the countershapemay be conveniently shaped to conform to the shape of face 906 or face907. In an embodiment, the countershape is preferably a “beanbag” thatcontains particles 924 and may be conformable to the shape of a moldface placed on top of it. Particles 924 may include ceramic material,metal material, glass beads, sand and/or salt. The particles preferablyfacilitate conductive heat to be applied to face 906 or face 907substantially evenly.

[0144] In an embodiment, the countershape 920 is preferably placed ontop of heat source 418. Countershape 920 is preferably heated until thetemperature of the countershape is substantially near or equal to thetemperature of the surface of the heat source. The countershape may thenbe “flipped over” such that the heated portion of the countershape thathas a temperature substantially near or equal to that of the surface ofthe heat source is exposed. A mold may be placed on top of the heatedportion of the countershape, and the countershape is preferablyconformed to the shape of the face of the mold. In this manner, the rateof conductive heat transfer to the lens may begin at a maximum. Heat ispreferably conductively transferred through the countershape and themold face to a face of the lens. The temperature of the heated portionof the countershape may tend to decrease after the mold is placed ontothe countershape.

[0145] In an embodiment, heat distributor 910 may partially insulate amold member from conductive heat source 418. The heat distributorpreferably allows a gradual, uniform transfer of heat to the moldmember. The heat distributor is preferably made of rubber and/or anothersuitable material. The heat distributor may include countershapes ofvarious shapes (e.g., hemispherically concave or convex) and sizes thatmay be adapted to contact and receive mold members.

[0146] In an embodiment, heat may be conductively applied by the heatsource to only one outside face of one mold member. This outside facemay be face 906 or face 907. Heat may be applied to the back face of thelens to enhance crosslinking and/or tintability of the lens materialproximate to the surface of the back face of the lens.

[0147] In a preferred embodiment, a thermostatically controlled hotplate 418 is preferably used as a heat source. Glass optical mold 928 ispreferably placed convex side up on hot plate 418 to serve as acountershape. The glass optical mold preferably has about an 80 mmdiameter and a radius of curvature of about 93 mm. Rubber disc 929 maybe placed over this mold 928 to provide uniform conductive heat to thelens mold assembly. The rubber disc is preferably made of silicone andpreferably has a diameter of approximately 74 mm and a thickness ofabout 3 mm. The lens mold assembly is preferably placed on mold 928 sothat outside face 906 of a mold member of the assembly rests on top ofmold 928. It is preferred that the edge of the lens mold assembly notdirectly contact the hot plate. The lens mold assembly preferablyreceives heat through the rubber disc and not through its mold edges.

[0148] To achieve good yield rates and reduce the incidence of prematurerelease while using the conductive heat method, it may be necessary forthe edge of the lens to be completely cured and dry before conductiveheat is applied. If the lens edge is incompletely cured (i.e., liquid orgel is still present) while conductive heat is applied, there may be ahigh incidence of premature release of the lens from the heating unit.

[0149] In an embodiment, the edges of a lens may be treated to cure orremove incompletely cured lens forming material (see above description)before conductive heat is applied. The mold cavity may be defined by atleast gasket 908, first mold member 902, and second mold member 904.Activating light rays may be directed toward at least one of the moldmembers, thereby curing the lens forming material to a lens preferablyhaving front face 916, a back face 915, and edges. Upon the formation ofthe lens, the gasket may be removed from the mold assembly. An oxygenbarrier may be used to cure any remaining liquid or gel on the lens edgeas described in more detail below. An oxygen barrier treated withphotoinitiator is preferably employed. Alternatively, any remainingliquid or gel may be removed manually. Once the edge of the lens is dry,a face of the lens may be conductively heated using any of the methodsdescribed herein.

[0150] In an embodiment, a lens may be tinted after receiving conductiveheat postcure treatment in a mold cavity. During tinting of the lens,the lens is preferably immersed in a dye solution.

[0151] The operation of the lens curing system may be controlled by amicroprocessor based controller 50 (FIG. 1). Controller 50 preferablycontrols the operation of coating unit 20, lens curing unit 30, andpost-cure unit 40. Controller 50 may be configured to substantiallysimultaneously control each of these units. In addition, the controllermay include a display 52 and an input device 54. The display and inputdevice may be configured to exchange information with an operator.

[0152] Controller 50 preferably controls a number of operations relatedto the process of forming a plastic lens. Many of the operations used tomake a plastic lens (e.g., coating, curing and post-cure operations) arepreferably performed under a predetermined set of conditions based onthe prescription and type of lens being formed (e.g.,ultraviolet/visible light absorbing, photochromic, colored, etc.).Controller 50 is preferably programmed to control a number of theseoperations, thus relieving the operator from having to continuallymonitor the apparatus.

[0153] In some embodiments, the lens or mold members may be coated witha variety of coatings (e.g., a scratch resistant or tinted coating). Theapplication of these coatings may require specific conditions dependingon the type of coating to be applied. Controller 50 is preferablyconfigured to produce these conditions in response to input from theoperator.

[0154] When a spin coating unit is used, controller 50 may be configuredto control the rotation of the lens or mold member during the coatingprocess. Controller 50 is preferably electronically coupled to the motorof the spin coating unit. The controller may send electronic signals tothe motor to turn the motor on and/or off. In a typical coating processthe rate at which the mold or lens is rotated is preferably controlledto achieve a uniform and defect free coating. The controller ispreferably configured to control the rate of rotation of the mold orlens during a curing process. For example, when a coating material isbeing applied, the mold or lens is preferably spun at relatively highrotational rates (e.g., about 900 to about 950 RPM). When the coatingmaterial is being cured, however, a much slower rotational rate ispreferably used (e.g., about 200 RPM). The controller is preferablyconfigured to adjust the rotational rate of the lens or mold dependingon the process step being performed.

[0155] The controller is also preferably configured to control theoperation of lamps 24. The lamps are preferably turned on and off at theappropriate times during a coating procedure. For example, during theapplication of the coating material activating lights are typically notused, thus the controller may be configured to keep the lamps off duringthis process. During the curing process, activating light may be used toinitiate the curing of the coating material. The controller ispreferably configured to turn the lamps on and to control the amount oftime the lamps remain on during a curing of the coating material. Thecontroller may also be configured to create light pulses to affectcuring of the coating material. Both the length and frequency of thelight pulses may be controlled by the controller.

[0156] The controller is also preferably configured to control operationof the lens-curing unit. The controller may perform some and/or all of anumber of functions during the lens curing process, including, but notlimited to: (i) measuring the ambient room temperature; (ii) determiningthe dose of light (or initial dose of light in pulsed curingapplications) required to cure the lens forming composition, based onthe ambient room temperature; (iii) applying the activating light withan intensity and duration sufficient to equal the determined dose; (iv)measuring the composition's temperature response during and subsequentto the application of the dose of light; (v) calculating the doserequired for the next application of activating light (in pulsed curingapplications); (vi) applying the activating light with an intensity andduration sufficient to equal the determined second dose; (vii)determining when the curing process is complete by monitoring thetemperature response of the lens forming composition during theapplication of activating light; (viii) turning the upper and lowerlight sources on and off independently; (ix) monitoring the lamptemperature, and controlling the temperature of the lamps by activatingcooling fans proximate the lamps; and (x) turning the fans on/off orcontrolling the flow rate of an air stream produced by a fan to controlthe composition temperature. Herein, “dose” refers to the amount oflight energy applied to an object, the energy of the incident lightbeing determined by the intensity and duration of the light.

[0157] A temperature monitor may be located at a number of positionswithin the lens curing unit 30. In one embodiment an infra-redtemperature sensor may be located such that it may measure thetemperature of the mold and/or the lens forming composition in the moldcavity. One infra-red temperature sensor may be the Cole-Parmer ModelE39669-00 (Vernon Hills, Ill.).

[0158] The temperature monitor may measure the temperature within thechamber and/or the temperature of air exiting the chamber. Thecontroller may be configured to send a signal to a cooler and/ordistributor to vary the amount and/or temperature of the cooling air.The temperature monitor may also determine the temperature at any of anumber of locations proximate the mold cavity. The temperature monitorpreferably sends a signal to the controller such that the temperature ofthe mold cavity and/or the lens forming composition may be relayed tothe controller throughout the curing process.

[0159] During the initial set-up of a curing process the temperature ofthe lens forming composition within the mold cavity may be determined.This initial temperature of the lens forming composition may be aboutequal to the ambient room temperature. The controller may then determinethe initial temperature of the lens forming composition by measuring theambient room temperature. Alternatively, the initial temperature of thelens forming composition may be measured directly using theaforementioned temperature sensors.

[0160] The controller preferably determines the initial dose to be givento the lens forming composition based on the initial temperature of thecomposition. The controller may use a table to determine the initialdose, the table including a series of values correlating the initialtemperature to the initial dose and/or the mass of the lens formingcomposition. The table may be prepared by routine experimentation. Toprepare the table a specific lens forming composition of a specific massis preferably treated with a known dose of activating light. The moldcavity is preferably disassembled and the gelation pattern of the lensforming composition observed. This procedure may be repeated, increasingor decreasing the dosage as dictated by the gelation patterns, until theoptimal dosage is determined for the specific lens forming composition.

[0161] During this testing procedure the initial temperature of the lensforming composition may be determined, this temperature being hereinreferred to as the “testing temperature”. In this manner, the optimaldose for the lens forming composition at the testing temperature may bedetermined. When the lens forming material has an initial temperaturethat is substantially equal to the testing temperature, the initialdosage may be substantially equal to the experimentally determineddosage. When the lens forming material has a temperature that issubstantially greater or less than the testing temperature, the initialdose may be calculated based on a function of the experimentallydetermined initial dose. In single dose applications the initial dose ofactivating light will be sufficient to substantially cure the plasticlens. For multi-pulse applications, the initial dose will be followed byadditional light doses.

[0162] In an embodiment, the controller is preferably adapted to controlthe intensity and duration of activating light pulses delivered from theactivating light source and the time interval between the pulses. Theactivating light source may include a capacitor which stores the energyrequired to deliver the pulses of activating light. The capacitor mayallow pulses of activating light to be delivered as frequently asdesired. A light sensor may be used to determine the intensity ofactivating light emanating from the source. The light sensor ispreferably adapted to send a signal to the controller, which ispreferably adapted to maintain the intensity of the activating light ata selected level. A filter may be positioned between the activatinglight source and the light sensor and is preferably adapted to inhibit aportion of the activating light rays from contacting the light sensor.This filter may be necessary to keep the intensity of the activatinglight upon the light sensor within the detectable range of the lightsensor.

[0163] In an embodiment, a shutter system may be used to control theapplication of activating light rays to the lens forming material. Theshutter system preferably includes air-actuated shutter plates that maybe inserted into the curing chamber to prevent activating light fromreaching the lens forming material. The shutter system may be coupled tothe controller, which may actuate an air cylinder to cause the shutterplates to be inserted or extracted from the curing chamber. Thecontroller preferably allows the insertion and extraction of the shutterplates at specified time intervals. The controller may receive signalsfrom temperature sensors allowing the time intervals in which theshutters are inserted and/or extracted to be adjusted as a function of atemperature of the lens forming composition and/or the molds. Thetemperature sensor may be located at numerous positions proximate themold cavity and/or casting chamber.

[0164] Alternatively, the shutter system may include an LCD filter thatmay be darkened to inhibit the activating light from reaching the lensforming material. The controller is preferably configured to darken theLCD panel at specified time intervals. The controller may receivesignals from temperature sensors allowing the time intervals in whichthe LCD panel is darkened to be adjusted as a function of a temperatureof the lens forming composition and/or the molds.

[0165] In an embodiment, a single dose of activating light may be usedto cure a lens forming composition. The controller may monitor thechange in temperature of the lens forming composition during theapplication of activating light. The activating light preferablyinitiates a polymerization reaction such that the temperature of thelens forming composition begins to rise. By monitoring the change intemperature over a time period the controller may determine the rate oftemperature change. The controller preferably controls thepolymerization of the lens forming composition based on the rate oftemperature change. When the temperature is found to be rising at afaster than desired rate, the desired rate being determined based onprevious experiments, the temperature controller may alter the intensityand/or the duration of the pulse such that the rate of temperaturechange is lowered. The duration of the activating light may be shortenedand/or the intensity of the activating light may be diminished toachieve this effect. The controller may also increase the rate ofcooling air blowing across the mold to help lower the temperature of thelens forming composition. Alternatively, if the temperature of thereaction is increasing too slowly, the controller may increase theintensity of the activating light and/or increase the duration of thepulse. Additionally, the controller may decrease the rate of cooling airblowing across the mold to allow the temperature of the lens formingcomposition to rise at a faster rate.

[0166] One manner in which the temperature may be controlled is bymonitoring the temperature during the application of activating light,as described in U.S. Pat. No. 5,422,046 to Tarshiani, et al. Duringactivating light irradiation, the temperature of the lens formingcomposition tends to rise. When the temperature reaches a predeterminedupper set point the activating light source is preferably turned off.Removal of the activating energy may allow the temperature to graduallybegin to fall. When the temperature is reduced to a predetermined lowerset point the activating light source is preferably turned on. In thismanner, the temperature may be controlled within a desired range. Thistemperature range tends to be very broad due to the nature of the lensforming polymerization reactions. For example, turning the activatinglight off at a predetermined upper set point may not insure that thetemperature of the lens forming composition will stop at that point. Infact, it is more likely that the temperature may continue to rise afterthe upper set point has been reached. To offset this effect the upperset point may be set at a temperature lower than the upper temperaturedesired during the lens forming process. Such a method of temperaturecontrol may be insufficient to control the temperature. As shown in FIG.17, increase in the temperature of a lens forming composition during thelens forming process may not be constant. Since the increase intemperature of the composition changes as the process continues, the useof an upper set point for controlling the temperature may not adequatelyprevent the composition from reaching greater than desired temperatures.Additionally, near the completion of the process the upper set point maybe set too low, thereby preventing the lens forming composition fromreaching a temperature that is adequate to maintain the polymerizationreaction due to insufficient doses of activating light.

[0167] In an embodiment the temperature control process may be describedas a modified Proportional-Integral-Derivative (“PID”) control method.Preferably, the controller is configured to operate the lens-curingsystem using a PID control method. The controller may use a number offactors to determine the dose of activating light applied for eachpulse. The controller preferably measures the temperature as well as therate of temperature change.

[0168] The PID control method involves the combination of proportional,integral and derivative controlling methods. The first, proportionalcontrol, may be achieved by mixing two control factors in such a way asto achieve the desired effect. For lens control the two factors whichtend to have the most effect on temperature control may be the dosage ofactivating light and the flow rate of the cooling air. These two factorsmay be altered to achieve a desired temperature response. If thetemperature must be raised as rapidly as possible a full dosage of lightmay delivered with no cooling air present. Similarly, if the compositionmust be rapidly cooled the sample may be treated with cooling air only.Preferably the two factors, application of incident light and cooling,are preferably both applied to achieve the desired temperature response.The mixture, or proportions of these factors may allow the temperatureof the composition to be controlled.

[0169] The use of proportional control tends to ignore other effectsthat influence the temperature of the lens forming composition. Duringthe lens forming process, the temperature of the lens formingcomposition may vary due to the rate of polymerization of the reaction.When the composition is undergoing a rapid rate of polymerization, thetemperature of the composition may rise beyond that determined by theproportional setting of the activating light and cooling air controls.Toward the end of the process the lens may become too cool due to the areduction in the rate of polymerization of the composition. The use ofproportional control may therefore be inadequate to control thisprocedure and may lead to greater than desired variations in thetemperature of the composition.

[0170] These limitations may be overcome by altering the proportions ofthe two components in response to the temperature of the composition. Asingle set point may be used to control the temperature of a reaction.As the temperature rises above this set point the proportion of theactivating light and cooling may be adjusted such that the temperaturebegins to lower back toward the set point. If the temperature dropsbelow the set point the proportion of activating light and cooling maybe adjusted to raise the temperature back to the set point. Typically,to lower the temperature the dose of activating light may be reducedand/or the flow rate of the cooling air may be increased. To raise thetemperature the dose of activating light may be increased and/or theflow rate of the cooling air may be decreased.

[0171] The use of proportional control in this manner may not lead to asteady temperature. Depending on the set point and the response time ofthe lens forming composition to variations in the dosage of light and/orcooling air, the temperature may oscillate over the set point, neverattaining a steady value. To better control such a system the rate ofchange of the temperature over a predetermined time period is preferablymonitored. As the temperature rises the rate at which the temperaturerises is preferably noted. Based on this rate of change the controllermay then alter the dosage of activating light and/or cooling air suchthat a temperature much closer to the set point may be achieved. Sincethe rate will change in response to changes in the rate ofpolymerization, such a system may better control the temperature of thelens forming composition throughout the process.

[0172] In an embodiment the controller may be a modified PID controlleror a computer programmed to control the lens curing unit using a PIDcontrol scheme. The controller preferably monitors the temperature ofthe lens forming composition throughout the process. Additionally, thecontroller may monitor the rate of change of temperature throughout thereaction. When a plurality of pulses are being applied to control thepolymerization, the controller preferably controls the duration andintensity of each pulse to control the temperature of the composition.In a typical process the rate of change in temperature is preferablymonitored after the application of an activating light pulse. If thetemperature is trending in an upward direction, the controllerpreferably waits for the temperature to crest and start descending,before the application of additional light pulses. This crestingtemperature may vary, as depicted in FIG. 17, throughout the lensforming process. After the temperature has passed a predetermined setpoint, a dose, calculated from the rate of change in temperature causedby the application of the previous pulse, may be applied to the lensforming composition. After the light pulse is delivered the controllermay repeat the procedure additional times.

[0173] When the reaction nears completion the controller detects thelack of response to the last exposure (i.e. the lens temperature did notincrease appreciably). At this point the controller may apply a finaldose to assure a substantially complete cure and notify the operatorthat the mold assembly is ready to be removed form the chamber.

[0174] One method of controlling the dose of light reaching the lens maybe through the use of filters, as described above. In one embodiment, anLCD filter system may be used to adjust the intensity of incoming light.The LCD system is preferably coupled to the controller such that apattern displayed by the LCD system may be altered by the controller.The controller preferably configures the pattern of light and dark areason the LCD panel such that light having the optimal curing intensitypattern hits the mold assemblies. The pattern that is produced ispreferably based on the prescription and type of lens being produced.

[0175] In another embodiment, the controller may actively change thepattern on the LCD panel during a curing cycle. For example, the patternof light and dark regions may be manipulated such that the lens is curedfrom the center of the lens then gradually expanded to the outer edgesof the lens. This type of curing pattern may allow a more uniformlycured lens to be formed. In some instances, curing in this manner mayalso be used to alter the final power of the formed lens.

[0176] In another embodiment, the LCD panel may be used as a partialshutter to reduce the intensity of light reaching the lens assembly. Byblackening the entire LCD panel the amount of light reaching any portionof the mold assembly may be reduced. The controller may be configured tocause the LCD panel to create “pulses” of light by alternating between atransmissive and darkened mode. By having the LCD panel create theselight “pulses” the need for a flash ballast or similar pulse generatingequipment may be unnecessary. Thus the use of a controller and an LCDpanel may simplify the system.

[0177] In some embodiments, the lens may require a post-curing process.The post-cure process may require specific conditions depending on thetype of lens being formed. The controller is preferably configured toproduce these conditions in response to input from the operator.

[0178] The controller is preferably configured to control the operationof lamps 440 (See FIG. 12). The lamps are preferably turned on and offat the appropriate times during the post-cure procedure. For example, insome post-cure operations the lights may not be required, thus thecontroller would keep the lights off during this process. During otherprocesses, the lights may be used to complete the curing of the lens.The controller is preferably configured to turn the lights on and tocontrol the amount of time the lights remain on during a post-cureprocedure. The controller may also be configured to create light pulsesduring the post-cure procedure. Both the length and frequency of thelight pulses may be controlled by the controller.

[0179] The controller is preferably configured to control operation ofthe heating device 418 during the post-cure operation. Heating device418 is preferably turned on and off to maintain a predeterminedtemperature within the post-cure unit. Alternatively, when a resistiveheater is used, the current flow through the heating element may bealtered to control the temperature within the post-cure unit. Preferablyboth the application of light and heat are controlled by the controller.The operation of fans, coupled to the post-cure unit, is also preferablycontrolled by the controller. The fans may be operated by the controllerto circulate air within or into/out of the post-cure unit.

[0180] Additionally, the controller may provide system diagnostics todetermine if the system is operating properly. The controller may notifythe user when routine maintenance is due or when a system error isdetected. For example, the controller may monitor the current passingthrough lamps of the coating, lens curing, or post-cure unit todetermine if the lamps are operating properly. The controller may keeptrack of the number of hours that the lamps have been used. When a lamphas been used for a predetermined number of hours a message may betransmitted to an operator to inform the operator that the lamps mayrequire changing. The controller may also monitor the intensity of lightproduced by the lamp. A photodiode may be placed proximate the lamps todetermine the intensity of light being produced by the lamp. If theintensity of light falls outside a predetermined range, the currentapplied to the lamp may be adjusted to alter the intensity of lightproduced (either increased to increase the intensity; or decreased todecrease the intensity). Alternatively, the controller may transmit amessage informing the operator that a lamp needs to be changed when theintensity of light produced by the lamp drops below a predeterminedvalue.

[0181] The controller may also manage an interlock system for safety andenergy conservation purposes. If the lens drawer assembly from thecoating or post-cure units are open the controller is preferablyconfigured to prevent the lamps from turning on. This may prevent theoperator from inadvertently becoming exposed to the light from thelamps. Lamps 24 for the coating unit 20 are preferably positioned oncover 22 (See FIG. 1). In order to prevent inadvertent exposure of theoperator to light from lamps 24 a switch is preferably built into thecover, as described above. The controller is preferably configured toprevent the lamps 24 from turning on when the cover is open. Thecontroller may also automatically turn lamps 24 off if the cover isopened when the lenses are on. Additionally, the controller may conserveenergy by keeping fans and other cooling devices off when the lamps areoff.

[0182] The controller may also be configured to interact with theoperator. The controller preferably includes an input device 54 and adisplay screen 52. The input device may be a keyboard (e.g., a fullcomputer keyboard or a modified keyboard), a light sensitive pad, atouch sensitive pad, or similar input device. A number the parameterscontrolled by the controller may be dependent on the input of theoperator. In the initial set up of the apparatus, the controller mayallow the operator to input the type of lens being formed. Thisinformation may include type of lens (clear, ultraviolet absorbing,photochromic, colored, etc.), prescription, and type of coatings (e.g.,scratch resistant or tint).

[0183] Based on this information the controller is preferably configuredto transmit information back to the operator. The operator may beinstructed to select mold members for the mold assembly. The moldmembers may be coded such that the controller may indicate to theoperator which molds to select by transmitting the code for each moldmember. The controller may also determine the type of gasket required toproperly seal the mold members together. Like the mold members, thegaskets may also be coded to make the selection of the appropriategasket easier.

[0184] The lens forming compositions may also be coded. For theproduction of certain kinds of lenses a specific lens formingcomposition may be required. The controller may be configured todetermine the specific composition required and transmit the code forthat composition to the operator. The controller may also signal to theoperator when certain operations need to be performed or when aparticular operation is completed (e.g., when to place the mold assemblyin the lens curing unit, when to remove the mold assembly, when totransfer the mold assembly, etc.).

[0185] Referring now to FIG. 38, another embodiment of a plastic lenscuring apparatus is generally indicated by reference numeral 1000. Asshown in FIG. 38, lens forming apparatus 1000 includes at least onecoating unit 1020, a pair of stacked lens curing units 1030 and 1035, apost-cure unit 1040, and a controller 1050. Preferably, apparatus 1000includes two coating units 1020. Coating unit 1020 is preferablyconfigured to apply a coating layer to a mold member or a lens.Preferably, coating unit 1020 is a spin coating unit. Each of the lenscuring units, 1030 and 1035, includes an activating light source forproducing activating light The activating light source is preferablyconfigured to direct light toward a mold assembly. Post-cure unit 1040is preferably configured to complete the polymerization of partiallycured plastic lenses. Post-cure unit 1040 preferably includes anactivating light source and a heat source. Controller 1050 is preferablya programmable logic controller. Controller 1050 is preferably coupledto coating units 1020, lens curing units 1030 and 1035, and post-cureunit 1040, such that the controller may be capable of substantiallysimultaneously operating the four units 1020, 1030, 1035 and 1040.Controller 50 may be a computer. During the production of plastic lensesthe lens curing step may be the most time consuming part of the process.By adding additional curing units to the system the throughput of thesystem may be increased, allowing the operator to form more lenses in agiven time period.

Lens Forming Compositions

[0186] The lens forming material may include any suitable liquid monomeror monomer mixture and any suitable photosensitive initiator. As usedherein “monomer” is taken to mean any compound capable of undergoing apolymerization reaction. Monomers may include non-polymerized materialor partially polymerized material. When partially polymerized materialis used as a monomer, the partially polymerized material preferablycontains functional groups capable of undergoing further reaction toform a new polymer. The lens forming material preferably includes aphotoinitiator that interacts with activating light. In one embodiment,the photoinitiator absorbs ultraviolet light having a wavelength in therange of 300 to 400 nm. In another embodiment, the photoinitiatorabsorbs actinic light having a wavelength in the range of about 380 nmto 490 nm. The liquid lens forming material is preferably filtered forquality control and placed in the lens molding cavity 382 by pulling theannular gasket 380 away from one of the opposed mold members 378 andinjecting the liquid lens forming material into the lens molding cavity382 (See FIG. 11). Once the lens molding cavity 382 is filled with suchmaterial, the annular gasket 380 is preferably replaced into its sealingrelation with the opposed mold members 378.

[0187] Those skilled in the art will recognize that once the cured lensis removed from the lens molding cavity 382 by disassembling the opposedmold members 378, the lens may be further processed in a conventionalmanner, such as by grinding its peripheral edge.

[0188] A polymerizable lens forming composition includes anaromatic-containing bis(allyl carbonate)-functional monomer and at leastone polyethylenic-functional monomer containing two ethylenicallyunsaturated groups selected from acrylyl or methacrylyl. In a preferredembodiment, the composition further includes a suitable photoinitiator.In other preferred embodiments, the composition may include one or morepolyethylenic-functional monomers containing three ethylenicallyunsaturated groups selected from acrylyl or methacrylyl, and a dye.

[0189] Aromatic-containing bis(allyl carbonate)-functional monomersinclude bis(allyl carbonates) of dihydroxy aromatic-containing material.The dihydroxy aromatic-containing material from which the monomer isderived may be one or more dihydroxy aromatic-containing compounds.Preferably the hydroxyl groups are attached directly to nuclear aromaticcarbon atoms of the dihydroxy aromatic-containing compounds. Themonomers are themselves known and may be prepared by procedures wellknown in the art.

[0190] The aromatic-containing bis(allyl carbonate)-functional monomersmay be represented by the formula:

[0191] in which A₁ is the divalent radical derived from the dihydroxyaromatic-containing material and each R₀ is independently hydrogen,halo, or a C₁-C₄ alkyl group. The alkyl group is usually methyl orethyl. Examples of R₀ include hydrogen, chloro, bromo, fluoro, methyl,ethyl, n-propyl, isopropyl and n-butyl. Most commonly R₀ is hydrogen ormethyl; hydrogen is preferred. A subclass of the divalent radical A₁which is of particular usefulness is represented by the formula:

[0192] in which each R₁ is independently alkyl containing from 1 toabout 4 carbon atoms, phenyl, or halo; the average value of each (a) isindependently in the range of from 0 to 4; each Q is independently oxy,sulfonyl, alkanediyl having from 2 to about 4 carbon atoms, oralkylidene having from 1 to about 4 carbon atoms; and the average valueof n is in the range of from 0 to about 3. Preferably Q ismethylethylidene, viz., isopropylidene.

[0193] Preferably the value of n is zero, in which case A₁ isrepresented by the formula:

[0194] in which each R₁, each a, and Q are as discussed in respect ofFormula II. Preferably the two free bonds are both in the ortho or parapositions. The para positions are especially preferred.

[0195] The dihydroxy aromatic-containing compounds from which A₁ isderived may also be polyether-functional chain extended compounds.Examples of such compounds include alkaline oxide extended bisphenols.Typically the alkaline oxide employed is ethylene oxide, propyleneoxide, or mixtures thereof. By way of exemplification, when para,para-bisphenols are chain extended with ethylene oxide, the bivalentradical A₁ may often be represented by the formula:

[0196] where each R₁ each a, and Q are as discussed in respect ofFormula II, and the average values of j and k are each independently inthe range of from about 1 to about 4.

[0197] A preferred aromatic-containing bis(allyl carbonate)-functionalmonomer is represented by the formula:

[0198] and is commonly known as bisphenol A bis(allyl carbonate).

[0199] A wide variety of compounds may be used as the polyethylenicfunctional monomer containing two or three ethylenically unsaturatedgroups. A preferred polyethylenic functional compound containing two orthree ethylenically unsaturated groups may be generally described as theacrylic acid esters and the methacrylic acid esters of aliphaticpolyhydric alcohols, such as, for example, the di- and triacrylates andthe di- and trimethacrylates of ethylene glycol, triethylene glycol,tetraethylene glycol, tetramethylene glycol, glycerol, diethyleneglycol,butyleneglycol, propyleneglycol, pentanediol, hexanediol,trimethylolpropane, and tripropyleneglycol. Examples of specificsuitable polyethylenic-functional monomers containing two or threeethylenically unsaturated groups include trimethylolpropanetriacrylate(TMPTA), tetraethylene glycol diacrylate (TTEGDA), tripropylene glycoldiacrylate (TRPGDA), 1,6 hexanedioldimethacrylate (HDDMA), andhexanedioldiacrylate (HDDA).

[0200] In general, a photoinitiator for initiating the polymerization ofthe lens forming composition preferably exhibits an absorption spectrumover the 300-400 nm range. High absorptivity of a photoinitiator in thisrange, however, is not desirable, especially when casting a thick lens.The following are examples of illustrative photoinitiator compounds:methyl benzoylformate, 2-hydroxy-2-methyl-1-phenylpropan-1-one,1-hydroxycyclohexyl phenyl ketone, 2,2-di-sec-butoxyacetophenone,2,2-diethoxyacetophenone, 2,2-diethoxy-2-phenyl-acetophenone,2,2-dimethoxy-2-phenyl-acetophenone, benzoin methyl ether, benzoinisobutyl ether, benzoin, benzil, benzyl disulfide,2,4-dihydroxybenzophenone, benzylideneacetophenone, benzophenone andacetophenone. Preferred photoinitiator compounds are 1-hydroxycyclohexylphenyl ketone (which is commercially available from Ciba-Geigy asIrgacure 184), methyl benzoylformate (which is commercially availablefrom Polysciences, Inc.), or mixtures thereof

[0201] Methyl benzoylformate is a generally preferred photoinitiatorbecause it tends to provide a slower rate of polymerization. The slowerrate of polymerization tends to prevent excessive heat buildup (andresultant cracking of the lens) during polymerization. In addition, itis relatively easy to mix liquid methyl benzoylformate (which is liquidat ambient temperatures) with many acrylates, diacrylates, and allylcarbonate compounds to form a lens forming composition. The lensesproduced with the methyl benzoylformate photoinitiator tend to exhibitmore favorable stress patterns and uniformity.

[0202] A strongly absorbing photoinitiator will absorb most of theincident light in the first millimeter of lens thickness, causing rapidpolymerization in that region. The remaining light will produce a muchlower rate of polymerization below this depth and will result in a lensthat has visible distortions. An ideal photoinitiator will exhibit highactivity, but will have a lower extinction coefficient in the usefulrange. A lower extinction coefficient of photoinitiators at longerwavelengths tends to allow the activating light to penetrate deeper intothe reaction system. This deeper penetration of the activating lightallows photoinitiator radicals to form uniformly throughout the sampleand provide excellent overall cure. Since the sample may be irradiatedfrom both top and bottom, a system in which appreciable activating lightreaches the center of the thickest portion of the lens is preferred. Thephotoinitiator solubility and compatibility with the monomer system isalso an important requirement.

[0203] An additional consideration is the effect of the photoinitiatorfragments in the finished polymer. Some photoinitiators generatefragments that impart a yellow color to the finished lens. Although suchlenses actually absorb very little visible light, they may becosmetically undesirable.

[0204] Photoinitiators are often very system specific so thatphotoinitiators that are efficient in one system may function poorly inanother. In addition, the initiator concentration, to a large extent,may be dependent on the incident light intensity and the monomercomposition. The identity of the initiator and its concentration may beimportant for any particular formulation. A concentration of initiatorthat is too high may lead to cracking and yellowing of the lens.Concentrations of initiator that are too low may lead to incompletepolymerization and a soft material.

[0205] Dyes and/or pigments are optional materials that may be presentwhen high transmission of light is not necessary.

[0206] The listing of optional ingredients discussed above is by nomeans exhaustive. These and other ingredients may be employed in theircustomary amounts for their customary purposes so long as they do notseriously interfere with good polymer formulating practice.

[0207] 1. Activating Light Curable Lens Forming Compositions

[0208] According to a preferred embodiment, a lens forming compositionthat may be cured with activating light includes an aromatic-containingbis(allyl carbonate) functional monomer, preferably bisphenol Abis(allyl carbonate), admixed with one or more faster reactingpolyethylenic functional monomers containing two acrylate ormethacrylate groups such as 1,6 hexanediol dimethacrylate (HDDMA), 1,6hexanediol diacrylate (HDDA), tetraethylene glycol diacrylate (TTEGDA),and tripropylene glycol diacrylate (TRPGDA) and optionally apolyethylenic functional monomer containing three acrylate groups suchas trimethylolpropane triacrylate (TMPTA). Generally, compoundscontaining acrylate groups polymerize much faster than those containingallyl groups.

[0209] According to one embodiment, the liquid lens forming compositionincludes bisphenol A bis(allyl carbonate) in place of DEG-BAC. Thebisphenol A bis(allyl-carbonate) monomer has a higher refractive indexthan DEG-BAC making it more suitable for the production of thinnerlenses, which may be important with relatively thick positive ornegative lenses. The bisphenol A bis(allyl-carbonate) monomer iscommercially available from PPG Industries under the trade name HIRII orCR-73. Lenses made from this product sometimes have a very slight,barely detectable, degree of yellowing. A small amount of a blue dyeconsisting of 9,10-anthracenedione, 1-hydroxy4-[(4-methylphenyl)amino]available as Thermoplast Blue 684 from BASF Wyandotte Corp. ispreferably added to the composition to counteract the yellowing. Inaddition, the yellowing tends to disappear if the lens is subjected tothe above-described post-cure heat treatment. Moreover, if notpost-cured the yellowing tends to disappear at ambient temperature afterapproximately 2 months.

[0210] TTEGDA, available from Sartomer and Radcure, is a diacrylatemonomer that, preferably, is included in the composition because it is afast polymerizing monomer that reduces yellowing and yields a very clearproduct. If too much TTEGDA is included in the more preferredcomposition, i.e., greater than about 25% by weight, however, thefinished lens may be prone to cracking and may be too flexible as thismaterial softens at temperatures above 40° C. If TTEGDA is excludedaltogether, the finished lens may be too brittle.

[0211] HDDMA, available from Sartomer, is a dimethacrylate monomer thathas a very stiff backbone between the two methacrylate groups. HDDMA,preferably, is included in the composition because it yields a stifferpolymer and increases the hardness and strength of the finished lens.This material is quite compatible with the bisphenol A bis(allylcarbonate) monomer. HDDMA contributes to high temperature stiffness,polymer clarity and speed of polymerization.

[0212] TRPGDA, available from Sartomer and Radcure, is a diacrylatemonomer that, preferably, is included in the composition because itprovides good strength and hardness without adding brittleness to thefinished lens. This material is also stiffer than TTEGDA.

[0213] TMPTA, available from Sartomer and Radcure, is a triacrylatemonomer that, preferably, is included in the composition because itprovides more crosslinking in the finished lens than the difunctionalmonomers. TMPTA has a shorter backbone than TTEGDA and increases thehigh temperature stiffness and hardness of the finished lens. Moreover,this material contributes to the prevention of optical distortions inthe finished lens. TMPTA also contributes to high shrinkage duringpolymerization. The inclusion of too much of this material in the morepreferred composition may make the finished lens too brittle.

[0214] Certain of the monomers that are preferably utilized, such asTTEGDA, TRPGDA and TMPTA, include impurities and have a yellow color incertain of their commercially available forms. The yellow color of thesemonomers is preferably reduced or removed by passing them through acolumn of alumina (basic) which includes aluminum oxide powder-basic.After passage through the alumina column differences between monomersobtained from different sources may be substantially eliminated. It ispreferred, however, that the monomers be obtained from a source whichprovides the monomers with the least amount of impurities containedtherein. The composition is preferably filtered prior to polymerizationthereof to remove suspended particles.

[0215] 2. Lens Forming Compositions Including Ultraviolet/Visible LightAbsorbing Materials

[0216] Materials that absorb various degrees of ultraviolet/visiblelight may be used in an eyeglass lens to inhibit ultraviolet/visiblelight from being transmitted through the eyeglass lens. The phrase“ultraviolet/visible light” is taken to mean light having a wavelengthin the ultraviolet light range or both the ultraviolet and visible lightranges. The phrase “ultraviolet/visible light absorbing compounds”refers to compounds which absorb ultraviolet/visible light. An eyeglasslens that includes ultraviolet/visible light absorbing compoundsadvantageously inhibits ultraviolet/visible light from being transmittedto the eye of a user wearing the lens. Thus, eyeglass lenses containingultraviolet/visible light absorbing compounds may function to protectthe eyes of a person from damaging ultraviolet/visible light.Photochromic pigments are one type of ultraviolet/visible lightabsorbing compounds. Photochromic inorganic lenses which contain silverhalide particles or cuprous halide particles suspended throughout thebody of the lens are well known and have been commercially available fordecades. Such inorganic lenses, however, suffer the disadvantage ofbeing relatively heavy and less comfortable to the wearer when comparedto organic lenses. Consequently, the majority of the eyeglass lensesproduced today are typically formed from organic materials rather thaninorganic materials. Accordingly, photochromic plastic eyeglass lenseshave been the subject of considerable attention in recent years.

[0217] Efforts to provide a plastic eyeglass lens which demonstratesphotochromic performance have primarily centered around permeatingand/or covering the surface(s) of an already formed lens withphotochromic pigments. This general technique may be accomplished by anumber of specific methods. For example, (a) the lens may be soaked in aheated bath which contains photochromic pigments, (b) photochromicpigments may be transferred into the surface of a plastic lens via asolvent assisted transfer process, or (c) a coating containingphotochromic pigments may be applied to the surface of a lens. A problemwith such methods may be that the lens often might not absorb enough ofthe photochromic pigments at low temperatures, resulting in an eyeglasslens which does not exhibit acceptable photochromic performance.Unfortunately, increasing the temperature used during absorption of thephotochromic pigments may not be a solution to this problem since athigh temperatures degradation of the polymer contained within the lensmay occur.

[0218] Attempts have also been made to incorporate photochromic pigmentsinto the liquid monomer from which plastic lenses are thermallypolymerized. See U.S. Pat. No. 4,913,544 to Rickwood et al., wherein itis disclosed that triethyleneglycol dimethacrylate monomer was combinedwith 0.2% by weight of various spiro-oxazine compounds and 0.1% benzoylperoxide and subsequently thermally polymerized to form non-prescriptioneyeglass lenses. Generally, efforts to incorporate photochromic pigmentsinto the liquid monomer from which the lenses are polymerized have beenunsuccessful. It is believed that the organic peroxide catalystsutilized to initiate the thermal polymerization reaction tend to damagethe photochromic pigments, impairing their photochromic response.

[0219] Curing of an eyeglass lens using activating light to initiate thepolymerization of a lens forming composition generally requires that thecomposition exhibit a high degree of activating light transmissibilityso that the activating radiation may penetrate to the deeper regions ofthe lens cavity. Otherwise the resulting cast lens may possess opticalaberrations and distortions. The cast lens may also contain layers ofcured material in the regions closest to the transparent mold faces,sandwiching inner layers which are either incompletely cured, gelled,barely gelled, or even liquid. Often, when even small amounts ofultraviolet/visible light absorbing compounds of the types well known inthe art are added to a normally light curable lens forming composition,substantially the entire amount of lens forming composition containedwithin the lens cavity may remain liquid in the presence of activatinglight.

[0220] Photochromic pigments which have utility for photochromiceyeglass lenses absorb ultraviolet light strongly and change from anunactivated state to an activated state when exposed to ultravioletlight. The presence of photochromic pigments, as well as otherultraviolet/visible light absorbing compounds within a lens formingcomposition, generally does not permit enough activating radiation topenetrate into the depths of the lens cavity sufficient to causephotoinitiators to break down and initiate polymerization of the lensforming composition. Thus, it may be difficult to cure a lens formingcomposition containing ultraviolet/visible light absorbing compoundsusing activating light (e.g., if the activating light has a wavelengthin the ultraviolet or visible region). It is therefore desirable toprovide a method for using activating light to initiate polymerizationof an eyeglass lens forming monomer which contains ultraviolet/visiblelight absorbing compounds, in spite of the high activating lightabsorption characteristics of the ultraviolet/visible light absorbingcompounds. Examples of such ultraviolet/visible light absorbingcompounds other than photochromic pigments are fixed dyes and colorlessadditives.

[0221] In an embodiment, an ophthalmic eyeglass lens may be made from alens forming composition comprising a monomer, an ultraviolet/visiblelight absorbing compound, a photoinitiator, and a co-initiator. Herein,an “ophthalmic eyeglass lens” is taken to mean any plastic eyeglasslens, including a prescription lens, a non-prescription lens, aprogressive lens, a sunglass lens, and a bifocal lens. The lens formingcomposition, in liquid form, is preferably placed in a mold cavitydefined by a first mold member and a second mold member. It is believedthat activating light which is directed toward the mold members toactivate the photoinitiator causes the photoinitiator to form a polymerchain radical. The polymer chain radical preferably reacts with theco-initiator more readily than with the monomer. The co-initiator mayreact with a fragment or an active species of either the photoinitiatoror the polymer chain radical to produce a monomer initiating species inthe regions of the lens cavity where the level of activating light maybe either relatively low or not present.

[0222] Preferably, the monomers selected as components of the lensforming composition are capable of dissolving the ultraviolet/visiblelight absorbing compounds added to them. Herein, “dissolving” is takento mean being substantially homogeneously mixed with. For example,monomers may be selected from a group including polyether (allylcarbonate) monomers, multi-functional acrylate monomers, andmulti-functional methacrylic monomers for use in an ultraviolet/visiblelight absorbing lens forming composition.

[0223] In an embodiment, the following mixture of monomers, hereinafterreferred to as PRO629, may be blended together before addition of othercomponents required to make the lens forming composition. This blend ofmonomers is preferably used as the basis for a lens forming compositionto which ultraviolet/visible light absorbing compounds are added.

[0224] 32% Tripropyleneglycol diacrylate (SR-306)

[0225] 21% Tetraethyleneglycol diacrylate (SR-268)

[0226] 20% Trimethylolpropane triacrylate (SR-351)

[0227] 17% Bisphenol A bis allyl carbonate (HiRi)

[0228] 10% Hexanediol dimethacrylate (SR-239)

[0229] The acrylic and methacrylic monomers listed above arecommercially available from Sartomer Company in Exton, Pa. The bisphenolA bis allyl carbonate is commercially available from PPG in Pittsburgh,Pa. The hexanediol dimethacrylate is hereinafter referred to as HDDMA.

[0230] A polymerization inhibitor may be added to the monomer mixture atrelatively low levels to inhibit polymerization of the monomer atinappropriate times (e.g., during storage). Preferably about 0 to 50 ppmof monomethylether hydroquinone (MEHQ) are added to the monomer mixture.It is also preferred that the acidity of the monomer mixture be as lowas possible. Preferably less than about 100 ppm residual acrylic acidexists in the mixture. It is also preferred that the water content ofthe monomer n be relatively low, preferably less than about 0.15%.

[0231] Photoinitiators include: 1-hydroxycyclohexylphenyl ketonecommercially available from Ciba Additives under the trade name ofIrgacure 184; mixtures of bis(2,6-dimethoxybenzoyl) (2,4,4-timethylphenyl)phosphine oxide and 2-hydroxy-2-methyl-1-phenyl-propan-1-onecommercially available from Ciba Additives under the trade name ofIrgacure 1700; mixtures of bis(2,6-dimethoxybenzoyl) (2,4,4 trimethylphenyl)phosphine oxide and 1-hydroxycyclohexylphenyl ketone commerciallyavailable from Ciba Additives under the trade names of Irgacure 1800 andIrgacure 1850; 2,2-dimethoxy-2-phenyl acetophenone commerciallyavailable from Ciba Additives under the trade name of Irgacure 651;2-hydroxy-2-methyl-1-phenyl-propan-1-one commercially available fromCiba Additives under the trade names of Darocur 1173; mixtures of2,4,6-trimethylbenzoyl-diphenylphoshine oxide and2-hydroxy-2-methyl-1-phenyl-propan-1-one commercially available fromCiba Additives under the trade name of Darocur 4265;2,2-diethoxyacetophenone REAP) commercially available from FirstChemical Corporation of Pascagoula, Miss., benzil dimethyl ketalcommercially available from Sartomer Company under the trade name ofKB-1; an alpha hydroxy ketone initiator commercially available fromSartomer company under the trade name of Esacure KIP100F; 2-methylthioxanthone (MTX), 2-chloro-thioxanthone (CTX), thioxanthone (TX), andxanthone, all commercially available from Aldrich Chemical;2-isopropyl-thioxanthone (ITX) commercially available from AcetoChemical in Flushing, New York; mixtures of triaryl sulfoniumhexafluoroantimonate and propylene carbonate commercially available fromSartomer Company under the trade names of SarCat CD 1010, SarCat 1011,and SarCat KI85; diaryliodinium hexafluoroantimonate commerciallyavailable from Sartomer Company under the trade name of SarCat CD-1012;mixtures of benzophenone and 1-hydroxycyclohexylphenyl ketonecommercially available from Ciba Additives under the trade name ofIrgacure 500;2-benzyl-2-N,N-dimethylamino-1-(4-morpholinophenyl)-1-butanonecommercially available from Ciba Additives under the trade name ofIrgacure 369;2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one commerciallyavailable from Ciba Additives under the trade name of Irgacure 907;bis(η5-2,4-cyclopentadien-1-yl)bis-[2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl]titaniumcommercially available from Ciba Additives under the trade name ofIrgacure 784 DC; mixtures of 2,4,6-trimethyl-benzophenone and4-methyl-benzophenone commercially available from Sartomer Company underthe trade name of EsaCure TZT; and benzoyl peroxide and methyl benzoylformate both available from Aldrich Chemical in Milwaukee, Wis.

[0232] A preferred photoinitiator is bis(2,6-dimethoxybenzoyl) (2,4,4timethyl phenyl) phosphine oxide, commercially available from CibaAdditives in Tarrytown, N.Y. under the trade name of CGI-819. The amountof CGI-819 present in a lens forming composition containing photochromiccompounds preferably ranges from about 30 ppm by weight to about 2000ppm by weight.

[0233] Co-initiators include reactive amine co-initiators commerciallyavailable from Sartomer Company under the trade names of CN-381, CN-383,CN-384, and CN-386, where these co-initiators are monoacrylic amines,diacrylic amines, or mixtures thereof. Other co-initiators includeN-methyldiethanolamine (NMDEA), triethanolamine (TEA),ethyl4-dimethylaminobenzoate (E4-DMAB), ethyl-2-dimethylaminobenzoate(E-2-DMAB), all commercially available from Aldrich Chemicals.Co-initiators which may also be used includen-butoxyethyl-4-dimethylamino benzoate-p-dimethyl amino benzaldehyde.Other co-initiators include N,N-dimethyl-p-toluidine,octyl-p-(dimethylamino) benzoate commercially available from The FirstChemical Group of Pascagoula, Miss.

[0234] Preferably, the co-initiator is N-methyldiethanolamine (NMDEA)commercially available from Aldrich Chemical in Milwaukee, Wis., CN-384commercially available from Sartomer Company, or CN-386 alsocommercially available from Sartomer Company. The quantity of NMDEApresent in a lens forming composition containing photochromic pigmentsis preferably between about 1 ppm by weight and 7% by weight and morepreferably between about 0.3% and 2% by weight. Further, certain fixedpigments which may be added to the lens forming composition to create abackground color within the lens (i.e., to tint the lens), may alsofunction as co-initiators. Examples of such fixed pigments includeThermoplast Blue P, Oil Soluble Blue II, Thermoplast Red 454,Thermoplast Yellow 104, Zapon Brown 286, Zapon Brown 287, allcommercially available from BASF Corporation in Holland, Mich.

[0235] Ultraviolet/visible light absorbing compounds which may be addedto a normally ultraviolet/visible light transmissible lens formingcomposition include 2-(2H benzotriazole-2-yl)-4-(1,1,3,3tetramethylbutyl)phenol and 2-hydroxy4-methoxybenzophenone, bothcommercially available from Aldrich Chemical as well as mixtures of2-[4-((2-hydroxy-3-dodecyloxypropyl)-oxy)-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazineand2-[4-((2-hydroxy-3-tridecyloxypropyl)-oxy)-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl-1,3,5-triazinecommercially available from Ciba Additives under the trade name ofTinuvin 400, mixtures of poly (oxy-1,2-ethanediyl),α-(3-(3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)4-hydroxyphenyl)-1-oxopropyl)-ω-hydroxyand poly(oxy-1,2-ethanediyl),α-(3-(3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)4-hydroxyphenyl)-1-oxopropyl)-ω-(3-(3-(2H-benzotriazol-2-yl)-5-1,1-dimethylethyl)-4-hydroxyphenyl)-1-oxopropoxy)commercially available from Ciba Additives under the trade name ofTinuvin 1130. Other ultraviolet/visible light absorbers may includeTinuvin 328, Tinuvin 900, 2-(2 hydroxy-5-methyl-phenyl)benzotriazole,ethyl-2-cyano 3,3-diphenyl acrylate, and phenyl salicylate.

[0236] While any number of families of photochromic pigments may beincorporated into the blend of monomers, either individually or incombination, spiropyrans, spironaphthoxazines, spiropyridobenzoxazines,spirobenzoxazines, napthopyrans, benzopyrans, spirooxazines,spironapthopyrans, indolinospironapthoxazines,indolinospironapthopyrans, diarylnapthopyrans, and organometallicmaterials are of particular interest A phenylmercury compound availablefrom Marks Polarized Corporation in Hauppauge, N.Y. under the trade nameof A241 may be an appropriate organometallic material. The quantity ofphotochromic pigments present in the lens forming composition ispreferably sufficient to provide observable photochromic effect. Theamount of photochromic pigments present in the lens forming compositionmay widely range from about 1 ppm by weight to 5% by weight. Inpreferred compositions, the photochromic pigments are present in rangesfrom about 30 ppm to 2000 ppm. In the more preferred compositions, thephotochromic pigments are present in ranges from about 150 ppm to 1000ppm. The concentration may be adjusted depending upon the thickness ofthe lens being produced to obtain optimal visible light absorptioncharacteristics.

[0237] In an embodiment, hindered amine light stabilizers may be addedto the lens forming composition. It is believed that these materials actto reduce the rate of degradation of the cured polymer caused byexposure to ultraviolet light by deactivating harmful polymer radicals.These compounds may be effective in terminating oxygen and carbon freeradicals, and thus interfering with the different stages ofauto-oxidation and photo-degradation. A useful hindered amine lightstabilizer is bis(1,2,2,6,6-pentamethyl-4-piperidinyl)-sebacatecommercially available from Ciba Additives under the trade name ofTinuvin 292. Hindered phenolic anti-oxidants and thermal stabilizers mayalso be added to a lens forming composition. The hindered phenoliccompounds hereof include thiodiethylenebis(3,5,-di-tert-butyl-4-hydroxy)hydroxycinnamate commercially availablefrom Ciba Additives under the trade name of Irganox 1035 andoctadecyl-3,5-bis(1,1-dimethylethyl)-4-hydroxybenzene-propanoatecommercially available from Ciba Additives under the trade name ofIrganox 1076.

[0238] Preferably, more than one monomer and more than one initiator areused in a lens forming composition to ensure that the initialpolymerization of the lens forming composition with activating lightdoes not occur over too short a period of time. The use of such a lensforming composition may allow greater control over the gel formation,resulting in better control of the optical quality of the lens. Further,greater control over the rate of exothermic heat generation may beachieved. Thus, cracking of the lens and premature release of the lensfrom the mold which are typically caused by the release of heat may beprevented. An example of a poor initiator system was observed whenCGI-819 was used alone as a photoinitiator in combination with thePRO-629 monomer blend to which ultraviolet/visible light absorbingcompounds had been added. When such an initiator system was used, a fastrate of reaction occurred near the surface of the lens cavity while avery slow rate of reaction occurred in the deeper regions of the cavity.The resultant lens exhibited unwanted waves and distortions.

[0239] In another example, a small amount of a co-initiator, i.e., NMDEAwas added to the above lens forming composition. During the curingprocess, two separate waves of heat were generated when the compositionwas irradiated continuously with activating light at about 600microwatts/cm². One possible explanation for this phenomena is that thefirst wave resulted from reaction of the NMDEA and the second waveresulted from the reaction of the unconsumed portion of the CGI-819.Another possible explanation is that the rate of reaction was faster inthe top portion than in the bottom portion of the lens formingcomposition since activating light was separately directed toward boththe bottom and the top mold members. A third wave of heat generation mayalso occur if the rate of reaction at the middle portion of the lensforming composition is different from the rates at the bottom and topportions. Unfortunately, the resulting lens possessed waves anddistortions. It is postulated, however, that as the amounts of bothCGI-819 and NMDEA are increased, the two waves of exothermic heat willmove closer together in time, causing the optical quality of the lens toimprove, the hardness of the lens to increase, and the rate of heatgeneration to be slow enough to prevent cracking and premature releaseof the lens from the mold.

[0240] It is anticipated that the optimal amount of initiators may beachieved when the total amount of both initiators are minimized subjectto the constraint of complete polymerization and production of a rigid,aberration free lens. The relative proportions of the photoinitiator tothe co-initiator may be optimized by experimentation. For example, anultraviolet/visible light absorptive lens forming composition thatincludes a photoinitiator with no co-initiator may be cured. If wavesand distortions are observed in the resulting lens, a co-initiator maythen be added to the lens forming composition by increasing amountsuntil a lens having the best optical properties is formed. It isanticipated that excess co-initiator in the lens forming compositionshould be avoided to inhibit problems of too rapid polymerization,yellowing of the lens, and migration of residual, unreacted co-initiatorto the surface of the finished lens.

[0241] The following charts may be used as a guide in the selection ofan appropriate photoinitiator/co-initiator system for variousultraviolet/visible light absorbing lens forming compositions.Photoinitiator Guide Lens Forming Composition Type UV Absorptive UVAbsorptive UV Absorptive Photoinitiator Yellowness Odor Shelf LifePhotochromic Fixed Pigments Colorless CGI 819 Moderate Low Good GoodGood Good Irgacure 184 Low Low Good Good Good Good Irgacure 651 High LowPoor Less Preferred Good Less Preferred Irgacure 1700 High Low Fair GoodGood Less Preferred Irgacure 1800 Moderate Low Good Good Good LessPreferred Irgacure 1850 Moderate Low Good Good Good Good Darocur 1173High Low Good Good Good Less Preferred Darocur 4265 High Moderate FairGood Good Less Preferred DEAP High Strong Poor Less Preferred LessPreferred Less Preferred KB-1 High Strong Poor Less Preferred LessPreferred Less Preferred EsaCure KIP100F High Strong Poor Less PreferredLess Preferred Less Preferred Irgacure 369 High Moderate Poor LessPreferred Good Less Preferred Irgacure 500 High Strong Poor LessPreferred Less Preferred Less Preferred Irgacure 784 DC High Low PoorLess Preferred Less Preferred Less Preferred Irgacure 907 High StrongPoor Less Preferred Less Preferred Less Preferred Benzoyl peroxideModerate Low Poor Less Preferred Less Preferred Less Preferred Methylbenzoyl formate Moderate Low Fair Less Preferred Less Preferred LessPreferred EsaCure TZT High Low Poor Less Preferred Less Preferred LessPreferred ITX High Low Poor Less Preferred Good Good MTX High Low PoorLess Preferred Good Good CTX High Low Poor Less Preferred Less PreferredLess Preferred TX High Low Poor Less Preferred Less Preferred LessPreferred Xanthone High Low Poor Less Preferred Less Preferred LessPreferred CD-1010 Low Low Poor Good Less Preferred Less PreferredCD-1011 Low Low Poor Good Less Preferred Less Preferred CD 1012 Low LowPoor Good Good Good

[0242] Co-initiator Guide Lens Forming Composition Type UV Absorptive UVAbsorptive UV Absorptive Co-initiator Photochromic Fixed PigmentsColorless CN-383 Good CN-384 Good Good Good CN-386 Good Good Good NMDEAGood Good Good N, NMDEA Less Preferred Less Preferred TEA Less PreferredLess Preferred E-4-DMAB Good Less Preferred Less Preferred E-2-DMAB LessPreferred Less Preferred

[0243] As mentioned above, exothermic reactions occur during the curingprocess of the lens forming composition. The thicker portions of thelens forming composition may generate more heat than the thinnerportions of the composition as a result of the exothermic reactionstaking place. It is believed that the speed of reaction in the thickersections is slower than in the thinner sections. Thus, in a positivelens a “donut effect” may occur in which the relatively thin outerportion of the lens forming composition reaches its fully cured statebefore the relatively thick inner portion of the lens formingcomposition. Conversely, in a negative lens the relatively thin innerportion of the lens forming composition may reach its fully cured statebefore the relatively thick outer portion of the lens formingcomposition.

[0244] An eyeglass lens formed using the above described lens formingcomposition may be applicable for use as a prescription lens or for anon-prescription lens. Particularly, such a lens may be used insunglasses. Advantageously, photochromic sunglass lenses would remainlight enough in color to allow a user to see through them clearly whileat the same time prohibiting ultraviolet light from passing through thelenses. In one embodiment, a background dye may be added to thephotochromic lens to make the lens appear to be a dark shade of color atall times like typical sunglasses.

[0245] 3. Variable Color Photochromic Lens Forming Compositions

[0246] Photochromic compounds tend to absorb certain wavelengths oflight strongly and change from a colorless state to a colored state. The“colorless state” of a photochromic compound is defined as the state inwhich the compound exhibits no color or only a slight amount of color.The “colored state” of a photochromic compound is defined as the statein which the photochromic compound exhibits a visible light colorsignificantly stronger than the colorless state. A “photochromicactivating light source” is defined as any light source that produceslight having a wavelength which causes a photochromic compound to changefrom a colorless state to a colored state. “Photochromic activatinglight” is defined as light having a wavelength capable of causing aphotochromic compound to change from a colorless state to a coloredstate. Photochromic activating light typically includes light having awavelength from between about 200 nm to about 500 nm. A photochromicactivating light source may also produce other wavelengths of light,besides photochromic activating light.

[0247] A photochromic compound which is transparent and normallycolorless will, upon exposure to a photochromic activating light source(e.g., ultraviolet light), become colored and, therefore, less visiblelight transmissive. When removed from the photochromic activating lightsource, the photochromic substance tends to revert back to its colorlessstate. This may be represented by the following equation:

[0248] The colorless form is believed to be in equilibrium with thecolored form. The equilibrium between the colorless form and the coloredform may be controlled by the presence of photochromic activating light(represented by hν). If a photochromic compound is exposed to aphotochromic activating light source, the equilibrium tends to shifttoward the colored form of the photochromic compound. When thephotochromic activating light source is removed, or reduced, or if thephotochromic compound is heated, the equilibrium tends to shift backtoward the colorless form of the photochromic compound. Photochromiccompounds of this type may be particularly useful in eyeglass lenses. Inthe absence of photochromic activating light (e.g., when indoors) theglasses tend to remain colorless and light transmissive. When exposed toa photochromic activating light source (e.g., sunlight) the photochromiccompounds become activated and colored, lowering the light transmittanceof the lens. The term “activated color” is defined as the color which aneyeglass attain when photochromic compounds, which are included in theeyeglass lens, become activated and colored when exposed to aphotochromic activating light source. In this manner, photochromiccompounds may allow a single lens to be used as both an indoor lens andan outdoor lens.

[0249] When incorporated into transparent plastic lenses and activatedby exposure to a photochromic activating light source, photochromiccompounds tend to exhibit variety of colors (e.g., red, orange, yellow,green, blue, indigo, purple, violet, gray, and brown), causing the lensthat the photochromic compounds are disposed within to exhibit the colorof the photochromic compound. Thus, the activated color of aphotochromic eyeglass lens may be controlled by the particularphotochromic compounds dispersed within the eyeglass lens.

[0250] It is known that the activated color of a photochromic eyeglasslens may take on more neutral colors, such as brown or gray, by formingthe eyeglass lens with two or more photochromic compounds present. U.S.Pat. No. 4,968,454 to Crano et. al., describes a composition whichincludes two photochromic compounds used to form plastic lenses. Theformed plastic lenses exhibit a gray or brown color in the presence of aphotochromic activating light source. Crano et. al., describes the useof two or more organic photochromic compounds within a plastic lens. Oneof the organic photochromic compounds exhibits an absorption maximum inthe range between about 590 nm to about 700 nm in the presence of aphotochromic activating light source. The other organic photochromiccompound exhibits an absorption maximum in the range between about 400nm and less than about 500 nm. The ratios of the compounds may be variedto produce lenses which exhibit a variety of activated colors.Typically, either the ratios of the photochromic compounds or thespecific photochromic compound used may be varied to effect a change inthe activated color of the lens.

[0251] In an embodiment, a composition which includes two or morephotochromic compounds may further include a light effector compositionto produce a lens which exhibits an activated color which differs froman activated color produced by the photochromic compounds without thelight effector composition. The light effector composition may includeany compound which absorbs photochromic activating light. Light effectorcompositions may include photoinitiators, non-photochromicultraviolet/visible light absorbers (as defined above), non-photochromicdyes, and ultraviolet light stabilizers. In this manner, the activatedcolor of a lens may be altered without altering the ratio and orcomposition of the photochromic compounds. This may be particularlyimportant when large batches of lens forming compositions are preparedbefore use. If photochromic lenses which exhibit a variety of activatedcolors are to be produced, it is typically necessary to create aseparate lens forming composition for each colored lens. By using alight effector composition, a single lens forming composition may beused as a base solution to which a light effector may be added in orderto alter the activated color of the formed lens.

[0252] The activated color of a photochromic lens may be determined bythe visible light absorption of the photochromic compounds in theircolored state. When two photochromic compounds are present, theequilibrium between the colored and the colorless forms may berepresented by the following equations:

[0253] Where PC¹ Colorless represents the colorless form of the firstphotochromic compound; PC² Colorless represents the colorless form ofthe second photochromic compound; PC light¹ represents the wavelengthsof light which cause PC¹ Colorless to shift its colored state (PC¹Colored); PC light² represents the wavelengths of light which cause PC¹Colorless to shift to its colored state (PC² Colored). As depicted inFIG. 37, the wavelength of light which may activate the photochromiccompounds PC¹ and PC² may differ depending on the chemical structure ofthe photochromic compounds. PC light¹, which activates the firstphotochromic compound PC¹, has a wavelength in the range between aboutλ¹ and λ² nm. PC light², which activates the second photochromiccompound, has a wavelength in the range between about λ³ and λ⁴ nm.These wavelength ranges may differ (as depicted in FIG. 37) or may besubstantially the same.

[0254] The addition of a light effector composition which absorbsphotochromic activating light may cause a change in the activated colorof the formed lens. The change in activated color may be dependent onthe range of photochromic activating light absorbed by the lighteffector composition. The addition of light effector compositions mayhave different effects on the activated color of the lens, depending onthe absorbance of the light effector composition. In one embodiment, thelight effector composition may interfere with the photochromic activityof the first photochromic compound (PC¹). As illustrated in theequations below, the presence of a light effector composition(Effector¹) may cause a shift in the equilibrium of PC¹ while havinglittle or no effect on PC².

[0255] Such an effect may cause an increase or decrease in theconcentration of PC¹ Colored produced when the lens is exposed to aphotochromic activating light source. The equilibrium of the otherphotochromic compound PC² may not be significantly altered. Thus, theactivated color of the lens may be significantly different than theactivated color of a lens that does not include a light effectorcomposition (Effector¹). In the above case, if the concentration of PC¹Colored is, for example, decreased, the activated color of the lens maybecome shifted toward the activated color of PC². For example, if theactivated color of a lens which includes PC¹ only is blue-green; withPC² only is red; and with both PC¹ and PC² is gray; the activated colorof the lens may become more red (e.g., shift from gray to green, yellow,orange or red) if the concentration of PC¹ Colored is decreased. It istheorized that such an effector may have an absorbance in a region oflight similar to the PC Light¹ region. The effector may interfere withthe absorption of photochromic activating light by PC¹ by competing withPC¹ for the light. PC² remains relatively unaffected by the lighteffector composition since its active photochromic activating lightrange differs significantly from the photochromic activating light rangefor PC¹. This is graphically illustrated in FIG. 37, where Effector¹ isdepicted as having an absorption within the PC¹ Light¹ region. Bycompeting with PC¹ for the photochromic activating light, Effector¹ maycause a decrease in the amount of PC¹ Colored being produced.

[0256] In another embodiment, a light effector may interact with bothphotochromic compounds, altering the amount of PC¹ colored and PC²colored produced. The equation below depicts this case:

[0257] Such an effect may cause an increase or decrease in theconcentration of both PC¹ Colored and PC² Colored produced when the lensis exposed to a photochromic activating light source. This change in theequilibrium may cause the activated color of the lens to besignificantly different than the activated color of a lens that does notinclude a light effector composition. In the above case if theconcentration of PC¹ Colored is, for example, decreased and theconcentration of PC² Colored is, for example, increased, the activatedcolor of the lens may become shifted toward the activated color of PC²colored. For example, if the activated color of a lens which includesPC¹ only is blue-green; with PC² only is red; and with both PC¹ and PC²is gray; the activated color of the lens may become more red in thepresence of the light effector composition. The direction of the shiftmay depend on which photochromic compound is effected more by thepresence of the light effector composition. It is theorized that thelight effector composition (Effector²) may have an absorbance in aregion that significantly overlaps the PC Light¹ and PC Light² regions.The light effector composition interferes with the absorption ofphotochromic activating light by both PC¹ and PC² by competing with thecompounds for light having the appropriate activating wavelength. If thelight effector interferes with the photochromic light absorption of PC¹to a greater extent then PC² the color may shift toward PC².Alternatively, the activated color may shift toward PC¹ if the lighteffector absorption interferes with the absorption of photochromic lightby PC² to a greater extent than PC¹. In FIG. 37, Effector² is depictedas having an absorption within both the PC¹ and PC² absorption region.

[0258] In another embodiment, a light effector composition may interferewith the photochromic activity of the second photochromic compound(PC²). As illustrated in the equations below, the presence of a lighteffector composition (Effector³) may cause a shift in the equilibrium ofPC² while having little or no effect on PC¹.

[0259] Such an effect may cause an increase or decrease in theconcentration of PC² Colored produced when the lens is exposed to aphotochromic activating light source. The equilibrium of the otherphotochromic compound PC¹ may not be significantly altered. In the abovecase, if the concentration of PC² Colored is, for example, decreased,the activated color of the lens may become shifted toward the activatedcolor of PC¹. For example, if the activated color of a lens whichincludes PC¹ only is blue-green; with PC² only is red; and with both PC¹and PC² is gray; the activated color of the lens may become more blue(e.g., shift from gray to green, green-blue, or blue) if theconcentration of PC¹ Colored is decreased. It is theorized that such aneffector may have an absorbance in a region of light similar to the PCLight² region. The effector may interfere with the absorption ofphotochromic activating light by PC² by competing with PC² for thelight. PC¹ remains relatively unaffected by the light effectorcomposition since its active photochromic activating light range differssignificantly from the photochromic activating light range for PC². Thisis graphically illustrated in FIG. 37, where Effector³ is depicted ashaving an absorption within the PC Light² region. By competing with PC²for the photochromic activating light, Effector³ may cause a decrease inthe amount of PC² Colored being produced.

[0260] While the above examples relate to the use of two photochromiccompounds, light effector compositions may be used to effect theactivated color of a lens which includes more than two photochromiccompounds. The color changes for these systems may be more varied thandescribed above, due to the variety of ranges in which the photochromiccompounds absorb the photochromic activating light. For example, ifthree photochromic compounds are present, with activated colors of red,blue and green, a variety of colors may be produced depending on theinteraction of the light effector composition with the photochromicactivating light. The light effector may absorb the photochromicactivating light such that the concentration of the colored form of twoof the three photochromic compounds is reduced. The formed lens wouldthan exhibit a color which is closest to the activated color of thenon-effected photochromic compound. In the above example, a lens with anactivated color of substantially blue, red, or green may be obtained bythe addition of a light effector. Alternatively, the light effectorcompound may reduce the concentration of the colored form of only one ofthe photochromic compounds. In the above example, the activated color ofthe lens may become yellow (from red and green, with reduced amount ofblue), green-blue (from green and blue, with reduced amount of red) orpurple (from red and blue, with reduced amount of green). A fullspectrum of activated colors may be produced by changing the compositionof the light effector composition, without having to alter the ratio orchemical composition of the photochromic compounds.

[0261] It should also be understood that the light effector compositionmay include one or more light effector compounds. The use of multiplelight effector compounds may allow the activated color of the lens to befurther altered.

[0262] In another embodiment, a photochromic activating light dye may beadded to the lens forming composition to alter the activated color of alens. The dye preferably exhibits a dye color when exposed to visiblelight. The dye color, however, is not significantly altered in thepresence or absence of photochromic activating light. When mixed with alens forming composition which includes at least one photochromiccompound the dye may alter the activated color of the lens, as well asthe color of the lens in the absence of photochromic activating light.

[0263] In one embodiment, the dye may interfere with the photochromicactivity of a photochromic compound. The activated color of a lensformed without the dye would preferably change when the dye is added tothe lens. The activated color of the lens may vary depending on the typeof dye chosen. In one embodiment, the dye may interfere with theabsorbance of photochromic activating light by the photochromiccompound. This interference may lead to a reduced concentration of thecolored form of the photochromic compound. The activated color of thelens may be a mixture of the dye color and the photochromic color. Forexample, if a dye is blue and the photochromic compound is red, the lensmay take on a purple color (i.e., a combination of the two colors).

[0264] It should be understood that the activated color of the lens maybe significantly different the an activated color of a lens in which thephotochromic compound is unaffected by the dye. When the absorption ofphotochromic activating light by the photochromic compound is unaffectedby the dye, the intensity of the colored form of the photochromiccompound may not be reduced. Thus, the activated color of the lens isformed from a mixture of the dye color and the full intensity of thecolored form of the photochromic compound. When the dye interferes withthe photochromic activating light absorbance of the photochromiccompound, the color of the lens is based on a combination of the dye andthe reduced intensity of the colored form of the photochromic compound.The reduced intensity of the colored form of the photochromic compoundmay cause the lens to have a color that is substantially different fromthe color produced when the unaffected colored form of the photochromiccompound is mixed with the dye.

[0265] While described above for one photochromic compound, it should beunderstood that the dye may have an effect on mixtures of photochromiccompounds such that a full spectrum of colors may be achieved. Theselection of the appropriate dye based on the photochromic compoundspresent allows the color of the lenses to be altered without changingthe ratio of the photochromic compounds.

[0266] In an embodiment, a lens forming composition includes at leasttwo photochromic compounds. The photochromic compounds are preferablychosen to that have an activated color at opposite ends of the visiblespectrum (e.g., blue and red). In one embodiment, the photochromiccompounds may be Reversacol Berry Red (giving a red activated color) andReversacol Sea Green (giving a blue-green color). The appropriatemixture of these two photochromic compounds gives the formed lens anactivated color of gray. The addition of effectors may cause the formedlens to have a wide variety of activated colors (e.g. red, orange,yellow, yellow green, green, aqua-green, blue, violet, purple, orbrown). These changes in color may be accomplished without altering theratio between the first and second photochromic compounds.

[0267] A lens forming composition based on the PRO-629 mixture ofmonomers may be used to develop photochromic lenses (See the sectionentitled “Lens Forming Compositions Including Ultraviolet/Visible LightAbsorbing Materials”). The remainder of the lens forming compositionpreferably includes photoinitiators, co-initiators, photochromiccompounds. The amount of photochromic pigments present in the lensforming composition may widely range from about 1 ppm by weight to 5% byweight. In preferred compositions, the photochromic pigments are presentin ranges from about 30 ppm to 2000 ppm. In the more preferredcompositions, the photochromic pigments are present in ranges from about150 ppm to 1000 ppm. The concentration may be adjusted depending uponthe thickness of the lens being produced to obtain optimal visible lightabsorption characteristics.

[0268] To alter the color of the active lens formed from this basecomposition a light effector composition may be added to the basecomposition. The light effector composition preferably includes one ormore light effectors. The light effector composition may be a purecomposition of one or more light effectors. Alternatively, the lighteffectors may be diluted in a solution which has a composition similarto the base composition. The light effectors preferably includephotochromic activating light absorbing compounds. More preferably,non-photochromic photochromic activating light absorbing compounds areadded to alter the activated color of the formed lens. Examples of lighteffectors include polymerization inhibitors (e.g., MEHQ),photoinitiators, co-initiators, fixed pigments and dyes, and hinderedamine light stabilizers. All of these classes of compounds are describedin greater detail in the previous section. After the light effectorcomposition has been added, the amount of light effectors present in thelens forming composition may widely range from about 1 ppm by weight to5% by weight. In preferred compositions, the light effectors are presentin ranges from about 30 ppm to 2000 ppm. In the more preferredcompositions, the light effectors are present in ranges from about 150ppm to 1000 ppm. The concentration may be adjusted depending upon thethickness of the lens being produced to obtain optimal visible lightabsorption characteristics.

[0269] An advantage of the described composition is that the activatedcolor of a lens may be altered without altering the ratio and orcomposition of the photochromic compounds. By using a light effectorcomposition, a single lens forming composition may be used as a basecomposition to which a light effector composition may be added in orderto alter the activated color of the formed lens. The base compositionmay be supplied for use in the production of a variety of photochromiclenses. Along with the base composition, a light effector composition,which includes one or more light effector compounds, may be includedwith the base composition. The light effector composition may be addedto the base composition to alter the activated color of the formedlenses. In this manner, a single stock photochromic lens formingcomposition may be used to create photochromic lenses having a varietyof activated colors.

[0270] In another embodiment, the base composition and at least twolight effector compositions may be package together as a kit. Theaddition of the first light effector composition may alter the activatedcolor of the formed lenses to produce a first color. The addition of thesecond light effector composition may alter the activated color of theformed lenses to produce a second color. Additional light effectorscompositions may also be included with the kit. The kit may allow a userto produce lens forming compositions which may be used to produce lenshaving a variety of activated colors by the addition of the appropriatelight effector composition to the base composition.

[0271] 4. Mid-Index Lens Forming Composition

[0272] In an embodiment, an ophthalmic eyeglass lens may be made from alens forming composition comprising a monomer composition and aphotoinitiator composition.

[0273] The monomer composition preferably includes an aromaticcontaining polyethylenic polyether functional monomer. In an embodiment,the polyether employed is an ethylene oxide derived polyether, propyleneoxide derived polyether, or mixtures thereof. Preferably, the polyetheris an ethylene oxide derived polyether. The aromatic polyetherpolyethylenic functional monomer preferably has the general structure(V), depicted below where each R₂ is a polymerizable unsaturated group,m and n are independently 1 or 2, and the average values of j and k areeach independently in the range of from about 1 to about 20. Commonpolymerizable unsaturated groups include vinyl, allyl, allyl carbonate,methacrylyl, acrylyl, methacrylate, and acrylate.

R₂—[CH₂—(CH₂)_(m)—O]_(j)—A₁—[O—(CH₂)_(n)—CH₂]_(k)—R₂

[0274] A₁ is the divalent radical derived from a dihydroxyaromatic-containing material. A subclass of the divalent radical A₁which is of particular usefulness is represented by formula (II):

[0275] in which each R₁ is independently alkyl containing from 1 toabout 4 carbon atoms, phenyl, or halo; the average value of each (a) isindependently in the range of from 0 to 4; each Q is independently oxy,sulfonyl, alkanediyl having from 2 to about 4 carbon atoms, oralkylidene having from 1 to about 4 carbon atoms; and the average valueof n is in the range of from 0 to about 3. Preferably Q ismethylethylidene, viz., isopropylidene.

[0276] Preferably the value of n is zero, in which case A₁ isrepresented by formula (III):

[0277] in which each R₁, each a, and Q are as discussed with respect toFormula II. Preferably the two free bonds are both in the ortho or parapositions. The para positions are especially preferred.

[0278] In an embodiment, when para, para-bisphenols are chain extendedwith ethylene oxide, the central portion of the aromatic containingpolyethylenic polyether functional monomer may be represented by theformula:

[0279] where each R₁, each a, and Q are as discussed with respect toFormula II, and the average values of j and k are each independently inthe range of from about 1 to about 20.

[0280] In another embodiment, the polyethylenic functional monomer is anaromatic polyether polyethylenic functional monomer containing at leastone group selected from acrylyl or methacrylyl. Preferably the aromaticpolyether polyethylenic functional monomer containing at least one groupselected from acrylate and methacrylate has the general structure (VI),depicted below where R₀ is hydrogen or methyl, where each R₁, each a,and Q are as discussed with respect to Formula II where the values of jand k are each independently in the range of from about 1 to about 20,and where R₂ is a polymerizable unsaturated group (e.g., vinyl, allyl,allyl carbonate, methacrylyl, acrylyl, methacrylate, or acrylate).

[0281] In one embodiment, the aromatic containing polyetherpolyethylenic functional monomer is preferably an ethoxylated bisphenolA di(meth)acrylate. Ethoxylated bisphenol A di(meth)acrylates have thegeneral structure depicted below where each R₀ is independently hydrogenor methyl, each R₁, each a, and Q are as discussed with respect toFormula II, and the values of j and k are each independently in therange of from about 1 to about 20.

[0282] Preferred ethoxylated bisphenol A dimethacrylates includeethoxylated 2 bisphenol A diacrylate (where j+k=2, and R₀ is H),ethoxylated 2 bisphenol A dimethacrylate (where j+k=2, and R₀ is Me),ethoxylated 3 bisphenol A diacrylate (where j+k=3, and R₀ is H),ethoxylated 4 bisphenol A diacrylate (where j+k=4, and R₀ is H),ethoxylated 4 bisphenol A dimethacrylate (where j+k=4, and R₀ is Me),ethoxylated 6 bisphenol A dimethacrylate (where j+k=6, and R₀ is Me),ethoxylated 8 bisphenol A dimethacrylate (where j+k=8, and R₀ is Me),ethoxylated 10 bisphenol A diacrylate (where j+k=10, and R₀ is H),ethoxylated 10 bisphenol A dimethacrylate (where j+k=10, and R₀ is Me),ethoxylated 30 bisphenol A diacrylate (where j+k=30, and R₀ is H),ethoxylated 30 bisphenol A dimethacrylate (where j+k=30, and R₀ is Me).These compounds are commercially available from Sartomer Company underthe trade names PRO-631, SR-348, SR-349, SR-601, CD-540, CD-541, CD-542,SR-602, SR-480, SR-9038, and SR-9036 respectively. Other ethoxylatedbisphenol A dimethacrylates include ethoxylated 3 bisphenol Adimethacrylate (where j+k=3, and R₀ is Me), ethoxylated 6 bisphenol Adiacrylate (where j+k=30, and R₀ is H), and ethoxylated 8 bisphenol Adiacrylate (where j+k=30, and R₀ is H). In all of the above describedcompounds Q is C(CH₃)₂.

[0283] The monomer composition preferably may also include apolyethylenic functional monomer. Polyethylenic functional monomers aredefined herein as organic molecules which include two or morepolymerizable unsaturated groups. Common polymerizable unsaturatedgroups include vinyl, allyl, allyl carbonate, methacrylyl, acrylyl,methacrylate, and acrylate. Preferably, the polyethylenic functionalmonomers have the general formula (VII) or (VIII) depicted below, whereeach R₀ is independently hydrogen, halo, or a C₁-C₄ alkyl group andwhere A₁ is as described above. It should be understood that whilegeneral structures (VII) and (VIII) are depicted as having only twopolymerizable unsaturated groups, polyethylenic functional monomershaving three (e.g., tri(meth)acrylates), four (e.g.,tetra(meth)acrylates), five (e.g., penta(meth)acrylates), six (e.g.,hexa(meth)acrylates) or more groups may be used.

[0284] Preferred polyethylenic functional monomers which may be combinedwith an aromatic containing polyethylenic polyether functional monomerto form the monomer composition include, but are not limited to,ethoxylated 2 bisphenol A dimethacrylate,tris(2-hydroxyethyl)isocyanurate triacrylate, ethoxylated 10 bisphenol Adimethacrylate, ethoxylated 4 bisphenol A dimethacrylate,dipentaerythritol pentaacrylate, 1,6-hexanediol dimethacrylate,isobornyl acrylate, pentaerythritol triacrylate, ethoxylated 6trimethylolpropane triacrylate, and bisphenol A bis allyl carbonate.

[0285] According to one embodiment, the liquid lens forming compositionincludes ethoxylated 4 bisphenol A dimethacrylate. Ethoxylated 4bisphenol A dimethacrylate monomer, when cured to form an eyeglass lens,typically produces lenses that have a higher index of refraction thancomparable lenses produced using DEG-BAC. Lenses formed from such amid-index lens forming composition which includes ethoxylated 4bisphenol A dimethacrylate may have an index of refraction of about 1.56compared to the PRO-629 compositions (previously described) which tendto have an index of refraction of about 1.51. A lens made from a higherindex of refraction polymer may be thinner than a lens made from a lowerindex of refraction polymer because the differences in the radii ofcurvature between the front and back surface of the lens do not have tobe as great to produce a lens of a desired focal power. Lenses formedfrom a lens forming composition which includes ethoxylated 4 bisphenol Adimethacrylate may also be more rigid than lenses formed from PRO-629based compositions.

[0286] The monomer composition may include additional monomers, which,when combined with ethoxylated 4 bisphenol A dimethacrylate, may modifythe properties of the formed eyeglass lens and/or the lens formingcomposition. Tris(2-hydroxyethyl)isocyanurate triacrylate, availablefrom Sartomer under the trade name SR-368, is a triacrylate monomer thatmay be included in the composition to provide improved clarity, hightemperature rigidity, and impact resistance properties to the finishedlens. Ethoxylated 10 bisphenol A dimethacrylate, available from Sartomerunder the trade name SR-480, is a diacrylate monomer that may beincluded in the composition to provide impact resistance properties tothe finished lens. Ethoxylated 2 bisphenol A dimethacrylate, availablefrom Sartomer under the trade name SR-348, is a diacrylate monomer thatmay be included in the composition to provide tintability properties tothe finished lens. Dipentaerythritol pentaacrylate, available fromSartomer under the trade name SR-399, is a pentaacrylate monomer thatmay be included in the composition to provide abrasion resistanceproperties to the finished lens. 1,6-hexanediol dimethacrylate,available from Sartomer under the trade name SR-239, is a diacrylatemonomer that may be included in the composition to reduce the viscosityof the lens forming composition. Isobornyl acrylate, available fromSartomer under the trade name SR-506, is an acrylate monomer that may beincluded in the composition to reduce the viscosity of the lens formingcomposition and enhance tinting characteristics. Bisphenol A bis allylcarbonate may be included in the composition to control the rate ofreaction during cure and also improve the shelf life of the lens formingcomposition. Pentaerythritol triacrylate, available from Sartomer underthe trade name SR-444, is a triacrylate monomer that may be included inthe composition to promote better adhesion of the lens formingcomposition to the molds during curing. Ethoxylated 6 trimethylolpropanetriacrylate, available from Sartomer under the trade name SR-454, mayalso be added.

[0287] Photoinitiators which may be used in the lens forming compositionhave been described in previous sections. In one embodiment, thephotoinitiator composition preferably includesbis(2,6-dimethoxybenzoyl)-(2,4,4-trimethylphenyl)phosphine oxide(IRG-819) which is commercially available from Ciba Additives under thetrade name of Irgacure 819. The amount of Irgacure 819 present in a lensforming composition preferably ranges from about 30 ppm by weight toabout 2000 ppm by weight. In another embodiment, the photoinitiatorcomposition may include a mixture of photoinitiator. Preferably, amixture of Irgacure 819 and 1-hydroxycyclohexylphenyl ketone,commercially available from Ciba Additives under the trade name ofIrgacure 184 (IRG-184),is used. Preferably, the total amount ofphotoinitiators in the lens forming composition ranges from about 50 ppmto about 1000 ppm.

[0288] In another embodiment, an ophthalmic eyeglass lens may be madefrom lens forming composition comprising a monomer composition, aphotoinitiator composition, and a co-initiator composition. The lensforming composition, in liquid form, is preferably placed in a moldcavity defined by a first mold member and a second mold member. It isbelieved that activating light which is directed toward the mold membersto activate the photoinitiator composition causes the photoinitiator toform a polymer chain radical. The co-initiator may react with a fragmentor an active species of either the photoinitiator or the polymer chainradical to produce a monomer initiating species. The polymer chainradical and the monomer initiating species may react with the monomer tocause polymerization of the lens forming composition.

[0289] The monomer composition preferably includes an aromaticcontaining polyethylenic polyether functional monomer having a structureas shown above. Preferably, the polyethylenic functional monomer is anaromatic polyether polyethylenic functional monomer containing at leastone group selected from acrylyl or methacrylyl.

[0290] More preferably, the polyethylenic functional monomer is anethoxylated bisphenol A di(meth)acrylate. The monomer composition mayinclude a mixture of polyethylenic functional monomers, as describedabove. The photoinitiators which may be present in the lens formingcomposition have been described above.

[0291] The lens forming composition preferably includes a co-initiatorcomposition. The co-initiator composition preferably includes amineco-initiators. Amines are defined herein as compounds of nitrogenformally derived from ammonia (NH₃) by replacement of the hydrogens ofammonia with organic substituents. Co-initiators include acrylyl amineco-initiators commercially available from Sartomer Company under thetrade names of CN-381, CN-383, CN-384, and CN-386, where theseco-initiators are monoacrylyl amines, diacrylyl amines, or mixturesthereof. Other co-initiators include ethanolamines. Examples ofethanolamines include but are not limited to N-methyldiethanolamine(NMDEA) and triethanolamine (TEA) both commercially available fromAldrich Chemicals. Aromatic amines (e.g., aniline derivatives) may alsobe used as co-initiators. Example of aromatic amines include, but arenot limited to, ethyl-4-dimethylaminobenzoate (E-4-DMAB),ethyl-2-dimethylaminobenzoate (E-2-DMAB),n-butoxyethyl-4-dimethylaminobenzoate, p-dimethylaminobenzaldehyde,N,N-dimethyl-p-toluidine, and octyl-p-(dimethylamino)benzoatecommercially available from Aldrich Chemicals or The First ChemicalGroup of Pascagoula, Miss.

[0292] Preferably, acrylated amines are included in the co-initiatorcomposition. Acrylyl amines may have the general structures depicted inFIG. 39, where R₀ is hydrogen or methyl, n and m are 1 to 20, preferably1-4, and R₁ and R₂ are independently alkyl containing from 1 to about 4carbon atoms or phenyl. Monoacrylyl amines may include at least oneacrylyl or methacrylyl group (see compounds (A) and (B) in FIG. 39).Diacrylyl amines may include two acrylyl, two methacrylyl, or a mixtureof acrylyl or methacrylyl groups (see compounds (C) and (D) in FIG. 39).Acrylyl amines are commercially available from Sartomer Company underthe trade names of CN-381, CN-383, CN-384, and CN-386, where theseco-initiators are monoacrylyl amines, diacrylyl amines, or mixturesthereof. Other acrylyl amines include dimethylaminoethyl methacrylateand dimethylaminoethyl acrylate both commercially available fromAldrich. In one embodiment, the co-initiator composition preferablyincludes a mixture of CN-384 and CN-386. Preferably, the total amount ofco-initiators in the lens forming composition ranges from about 50 ppmto about 7% by weight.

[0293] An advantage to lens forming compositions which include aco-initiator is that less photoinitiator may be used to initiate curingof the lens forming composition. Typically, plastic lenses are formedfrom a lens forming composition which includes a photoinitiator and amonomer. To improve the hardness of the formed lenses the concentrationof photoinitiator may be increased. Increasing the concentration ofphotoinitiator, however, may cause increased yellowing of the formedlens, as has been described previously. To offset this increase inyellowing, a permanent dye may be added to the lens forming composition.As the amount of yellowing is increased the amount of dye added mayalso. be increased. Increasing the concentration of the dye may causethe light transmissibility of the lens to decrease.

[0294] A lens forming composition that includes a co-initiator may beused to reduce the amount of photoinitiator used. To improve thehardness of the formed lenses a mixture of photoinitiator andco-initiator may be used to initiate curing of the monomer. Theabove-described co-initiators typically do not significantly contributeto the yellowing of the formed lens. By adding co-initiators to the lensforming composition, the amount of photoinitiator may be reduced.Reducing the amount of photoinitiator may decrease the amount ofyellowing in the formed lens. This allows the amount of dyes added tothe lens forming composition to be reduced and light transmissibility ofthe formed lens may be improved without sacrificing the rigidity of thelens.

[0295] The lens forming composition may also include activating lightabsorbing compounds. These compounds may absorb at least a portion ofthe activating light which is directed toward the lens formingcomposition during curing. One example of activating light absorbingcompounds are photochromic compounds. Photochromic compounds which maybe added to the lens forming composition have been previously described.Preferably, the total amount of photochromic compounds in the lensforming composition ranges from about 1 ppm to about 1000 ppm. Examplesof photochromic compounds which may be used in the lens formingcomposition include, but are not limited to Corn Yellow, Berry Red, SeaGreen, Plum Red, Variacrol Yellow, Palatinate Purple, CH-94, VariacrolBlue D, Oxford Blue and CH-266. Preferably, a mixture of these compoundsis used. Variacrol Yellow is a napthopyran material, commerciallyavailable from Great Lakes Chemical in West Lafayette, Ind. Corn Yellowand Berry Red are napthopyrans and Sea Green, Plum Red and PalatinatePurple are spironaphthoxazine materials commercially available fromKeystone Aniline Corporation in Chicago, Ill. Variacrol Blue D andOxford Blue are spironaphthoxazine materials, commercially availablefrom Great Lakes Chemical in West Lafayette, Ind. CH-94 and CH-266 arebenzopyran materials, commercially available from Chroma Chemicals inDayton, Ohio. The composition of a Photochromic Dye Mixture which may beadded to the lens forming composition is described in the table below.Photochromic Dye Mixture Corn Yellow 22.3% Berry Red 19.7% Sea Green14.8% Plum Red 14.0% Variacrol Yellow  9.7% Palatinate Purple  7.6%CH-94  4.0% Variacrol Blue D  3.7% Oxford Blue  2.6% CH-266  1.6%

[0296] The lens forming composition may also other activating lightabsorbing compounds such as UV stabilizers, UV absorbers, and dyes. UVstabilizers, such as Tinuvin 770 may be added to reduce the rate ofdegradation of the formed lens caused by exposure to ultraviolet light.UV absorbers, such as2-(2H-benzotriazol-2-yl)-4-(1,1,3,3,-tetramethylbutyl)phenol, may beadded to the composition to provide UV blocking characteristics to theformed lens. Small amounts of dyes, such as Thermoplast Blue 684 andThermoplast Red from BASF may be added to the lens forming compositionto counteract yellowing. These classes of compounds have been describedin greater detail in previous sections.

[0297] In an embodiment, a UV absorbing composition may be added to thelens forming composition. The UV absorbing composition preferablyincludes a photoinitiator and a UV absorber. Photoinitiators and UVabsorbers have been described in greater detail in previous sections.Typically, the concentration of UV absorber in the lens formingcomposition required to achieve desirable UV blocking characteristics isin the range from about 0.1 to about 0.25% by weight. For example,2-(2H-benzotriazol-2-yl)-4-(1,1,3,3,-tetramethylbutyl)phenol may beadded to the lens forming composition as a UV absorber at aconcentration of about 0.17%.

[0298] By mixing a photoinitiator with a UV absorbing compound thecombined concentration of the photoinitiator and the UV absorberrequired to achieve the desired UV blocking characteristics in theformed lens may be lower than the concentration of UV absorber requiredif used alone. For example,2-2H-benzotriazol-2-yl)-4-(1,1,3,3,-tetramethylbutyl)phenol may be addedto the lens forming composition as a UV absorber at a concentration ofabout 0.17% to achieve the desired UV blocking characteristics for theformed lens. Alternatively, a UV absorbing composition may be formed bya combination of2-(2H-benzotriazol-2-yl)-4-(1,1,3,3,-tetramethylbutyl)phenol with thephotoinitiator 2-isopropyl-thioxanthone (ITX), commercially availablefrom Aceto Chemical in Flushing, N.Y. To achieve similar UV blockingcharacteristics in the formed lens, significantly less of the UVabsorbing composition may be added to the lens forming composition,compared to the amount of UV absorber used by itself. For example,2-(2H-benzotriazol-2-yl)-4-(1,1,3,3,-tetramethylbutyl)phenol at aconcentration of about 700 ppm, with respect to the lens formingcomposition, along with 150 ppm of the photoinitiator2-isopropyl-thioxanthone (2-ITX) may be used to provide UV blockingcharacteristics. Thus, a significant reduction, (e.g., from 0.15% downto less than about 1000 ppm), in the concentration of UV absorber may beachieved, without a reduction in the UV blocking ability of thesubsequently formed lens. An advantage of lowering the amount of UVabsorbing compounds present in the lens forming composition is that thesolubility of the various components of the composition may be improved.

[0299] The tables below list some examples of mid-index lens formingcompositions. The UV absorber is2-(2H-benzotriazol-2-yl)-4-(1,1,3,3,-tetramethylbutyl)phenol. IngredientFormula 1 Formula 2 Formula 3 Formula 4 Formula 5 Formula 6 Irgacure 819694.2 ppm   486 ppm   480 ppm   382 ppm  375 ppm  414 ppm Irgacure 184CN 384 0.962% 0.674% 0.757% 0.62% 0.61% 0.66% CN 386 0.962% 0.674%0.757% 0.62% 0.61% 0.66% SR-348 97.98% 68.65%  98.2% 81.2% 79.6% 86.4%SR-368 SR-480 29.95% CD-540 SR-399 SR-239  2.0% 2.08% SR-506 CR-73 17.2%16.9% 10.0% PRO-629 Tinuvin 770   290 ppm UV Absorber 0.173% Thermoplast0.534 ppm  0.374 ppm  0.6 ppm  0.5 ppm  4.5 ppm 4.58 ppm BlueThermoplast 0.019 ppm 0.0133 ppm 0.015 ppm 0.012 ppm 0.58 ppm 0.58 ppmRed Mineral Oil   136 ppm   65 ppm Photochromic  470 ppm  507 ppm DyeMixture Ingredient Formula 7 Formula 8 Formula 9 Formula 10 Formula 11Formula 12 Irgacure 819  531.2 ppm   462 ppm 565.9 ppm   226 ppm   443ppm  294 ppm Irgacure 184  18.7 ppm   144 ppm CN 384 0.77% 0.887% 0.78%0.40% 0.61% CN 386 0.77% 0.887% 0.78% 0.53% 0.61% SR-348 72.4% 70.36%58.20%  41.5% 88.70%  SR-368 24.1% 23.87% 21.4%  7.0% SR-480 CD-54018.7% 0.74% 97.76%  SR-399 46.8% SR-239 1.86%  3.65% 20.1% 2.00% SR-50610.0% CR-73 20.1%  2.9% PRO-629 0.05% Tinuvin 770 UV AbsorberThermoplast  0.567 ppm  3.62 ppm  0.70 ppm 0.255 ppm  0.6 ppm  4.3 ppmBlue Thermoplast 0.0147 ppm 0.576 ppm 0.014 ppm 0.006 ppm 0.028 ppm 0.24ppm Red Photochromic   450 ppm Dye Mixture Ingredient Formula 13 Formula14 Formula 15 Formula 16 Formula 17 Formula 18 Irgacure 819   760 ppm  620 ppm   289 ppm  105 ppm   343 ppm Irgacure 184 CN 384 0.73% 0.34%0.475% CN 386 0.73% 0.34%  1.00% 0.70% 0.475% 2-ITX   188 ppm   141 ppmSR-348 89.00% 92.00%  98.90% SR-368 SR-480 CD-540 97.57%  96.20% 99.28%  0.34% SR-399 SR-239 2.30% 2.30% 0.01% SR-506 SR-444 SR-45410.00%  6.9% CR-73 PRO-629 Tinuvin 770 UV Absorber   785 ppm Thermoplast 4.9 ppm  5.1 ppm 0.508 ppm  0.35 ppm  0.69 ppm Blue Thermoplast 0.276ppm 0.285 ppm 0.022 ppm 0.002 ppm 0.034 ppm Red Dioctyl-   125 ppmphthalate Butyl stearate Photochromic   499 ppm Dye Mixture IngredientFormula 19 Formula 20 Formula 21 Formula 22 Formula 23 Formula 24Irgacure 819   490 ppm   635 ppm   610 ppm  735 ppm   320 ppm   600 ppmIrgacure 184 CN 384 0.680% 0.746% 0.705% 0.60% CN 386 0.680% 0.746%0.705% 0.60% 2-ITX SR-348 69.30% 68.60% SR-368 74.0% 22.10% SR-480CD-540 98.45% 92.60% 98.50%   1.0%  1.97% SR-399 SR-239  0.01%  3.86%0.16% SR-506 0.10% SR-444 29.30% SR-454 25.0%  7.40% CR-73 PRO-6290.007%  2.06% Tinuvin 770 UV Absorber Thermoplast  0.37 ppm  0.507 ppm 3.07 ppm  4.3 ppm  0.15 ppm  0.29 ppm Blue Thermoplast 0.013 ppm 0.0126ppm 0.336 ppm 0.41 ppm 0.006 ppm 0.012 ppm Red Dioctyl- phthalate Butylstearate Photochromic   442 ppm  497 ppm Dye Mixture Ingredient Formula25 Formula 26 Formula 27 Formula 28 Formula 29 Formula 30 Formula 31Irgacure 819   650 ppm   464 ppm  557 ppm   448 ppm   460 ppm Irgacure184 300 ppm CN 384 0.650%  0.70% CN 386 0.650%  0.70% 2-ITX 600 ppm 120ppm SR-348 39.10% SR-368 13.00% 19.60% 20.70% SR-480 10.70% CD-54088.96% 41.90% 1.60%  1.30% 99.94% 99.96% SR-399 SR-239 SR-506 98.30%79.00% 67.24% SR-444  9.70%  4.60% SR-454 CR-73 PRO-629 Tinuvin 770 UVAbsorber Thermoplast 0.566 ppm  0.52 ppm 0.24 ppm  0.19 ppm 0.467 ppmBlue Thermoplast  0.02 ppm 0.013 ppm 0.01 ppm 0.008 ppm 0.024 ppm RedDioctyl- phthalate Butyl stearate   75 ppm   35 ppm Photochromic DyeMixture

[0300] In one embodiment, plastic lenses may be formed by disposing amid-index lens forming composition into the mold cavity of a moldassembly and irradiating the mold assembly with activating light.Coating materials may be applied to the mold members prior to fillingthe mold cavity with the lens forming composition.

[0301] After filing the mold cavity of the mold assembly the moldassembly is preferably placed in the lens curing unit and subjected toactivating light. Preferably, actinic light is used to irradiate themold assembly. A clear polycarbonate plate may be placed between themold assembly and the activating light source. The polycarbonate platepreferably isolates the mold assembly from the lamp chamber, thuspreventing airflow from the lamp cooling fans from interacting with themold assemblies. The activating light source may be configured todeliver from about 0.1 to about 10 milliwatts/cm2 to at least onenon-casting face, preferably both non-casting faces, of the moldassembly. Depending on the components of the lens forming compositionused the intensity of activating light used may be <1 milliwatt/cm². Theintensity of incident light at the plane of the lens curing unit draweris measured using an International Light IL-1400 radiometer equippedwith an XRL140A detector head. This particular radiometer preferably hasa peak detection wavelength at about 400 nm, with a detection range fromabout 310 nm to about 495 nm. The International Light IL-1400 radiometerand the XRL140A detector head are both commercially availableInternational Light, Incorporated of Newburyport, Mass.

[0302] After the mold assembly is placed within the lens curing unit,the mold assemblies are preferably irradiated with activating lightcontinuously for 30 seconds to thirty minutes, more preferably from oneminute to five minutes. Preferably, the mold assemblies irradiated inthe absence of a cooling air stream. After irradiation, the moldassemblies were removed from the lens curing unit and the formed lensdemolded. The lenses may be subjected to a post-cure treatment in thepost-cure unit.

[0303] In general, it was found that the use of a photoinitiator (e.g.,IRG-819 and IRG-184) in the lens forming composition produces lenseswith better characteristics than lens formed using a co-initiator only.For example, formula 15, described in the above table, includes amonomer composition ( a mixture of SR-348 and SR-454) and a co-initiator(CN-386). When this lens forming composition was exposed to activatinglight for 15 min. there was no significant reaction or gel formation. Itis believed that the co-initiator requires an initiating species inorder to catalyze curing of the monomer composition. Typically thisinitiating species is produced from the reaction of the photoinitiatorwith activating light.

[0304] A variety of photoinitiators and photoinitiators combined withco-initiators may be used to initiate polymerization of the monomercomposition. One initiator system which may be used includesphotoinitiators IRG-819 and 2-ITX and a co-initiator, see Formulas17-18. Such a system is highly efficient at initiating polymerizationreactions. The efficiency of a polymerization catalyst is a measurementof the amount of photoinitiator required to initiate a polymerizationreaction. A relatively small amount of an efficient photoinitiator maybe required to catalyze a polymerization reaction, whereas a greateramount of a less efficient photoinitiator may be required to catalyzethe polymerization reaction. The IRG-819/2-ITX/co-initiator system maybe used to cure lenses forming compositions which include a UV absorbingcompound. This initiator system may also be used to form colored lenses.

[0305] An initiator system that is less efficient than theIRG-819/2-ITX/co-initiator system includes a mixture of thephotoinitiators IRG-819 and 2-ITX, see Formula 31. This system is lessefficient at initiating polymerization of lens forming compositions thanthe IRG-819/2-ITX/co-initiator system. The IRG-819/2-ITX system may beused to cure very reactive monomer compositions. An initiator systemhaving a similar efficiency to the IRG-819/2-ITX system includes amixture of IRG-819 and co-initiator, see Formulas 1-6, 8-9, 11, 14-15,19-22, and 25-26. The IRG-819/co-initiator system may be used to cureclear lenses which do not include a UV blocking compound andphotochromic lens forming compositions.

[0306] Another initiator system which may be used includes thephotoinitiator 2-ITX and a co-initiator. This initiator system is muchless efficient at initiating polymerization reactions than theIRG-819/co-initiator system. The 2-ITX/co-initiator system is preferablyused for curing monomer compositions which include highly reactivemonomers.

[0307] The use of the above described mid-index lens formingcompositions may minimize or eliminate a number of problems associatedwith activating light curing of lenses. One problem typical of curingeyeglass lenses with activating light is pre-release. Pre-release may becaused by a number of factors. If the adhesion between the mold facesand the shrinking lens forming composition is not sufficient,pre-release may occur. The propensity of a lens forming composition toadhere to the mold face, in combination with its shrinkage, determinehow the process variables are controlled to avoid pre-release. Adhesionis affected by such factors as geometry of the mold face (e.g., high-addflattop bifocals tend to release because of the sharp change in cavityheight at the segment line), the temperature of the mold assembly, andthe characteristics of the in-mold coating material. The processvariables which are typically varied to control pre-release include theapplication of cooling fluid to remove exothermic heat, controlling therate of heat generation by manipulating the intensities and timing ofthe activating radiation, providing differential light distributionacross the thin or thick sections of the mold cavity manipulating thethickness of the molds, and providing in-mold coatings which enhanceadhesion. An advantage of the above described mid-index lens formingcompositions is that the composition appears to have enhanced adhesioncharacteristics. This may allow acceptable lenses to be produced over agreater variety of curing conditions. Another advantage is that higherdiopter lenses may be produced at relatively low pre-release rates,broadening the achievable prescription range.

[0308] Another advantage of the above described mid-index lens formingcompositions is that they tend to minimize problems associated withdripping during low intensity curing of lenses (e.g., in the 1 to 6milliwatt range). Typically, during the irradiation of the lens formingcomposition with activating light, small amounts of monomer may besqueezed out of the cavity and run onto the non-casting faces of themolds. Alternatively, during filling of the mold assembly with the lensforming composition, a portion of the lens forming composition may driponto the non-casting faces of the mold assembly. This “dripping” ontothe non-casting faces of the mold assembly tends to cause the activatinglight to focus more strongly in the regions of the cavity locatedunderneath the drippings. This focusing of the activating light mayaffect the rate of curing. If the rate of curing underneath thedrippings varies significantly from the rate of curing throughout therest of the lens forming composition, optical distortions may be createdin the regions below the drippings.

[0309] It is believed that differences in the rate of gelation betweenthe center and the edge regions of the lens forming composition maycause dripping to occur. During the curing of a lens formingcomposition, the material within the mold cavity tends to swell slightlyduring the gel phase of the curing process. If there is enough residualmonomer around the gasket lip, this liquid will tend to be forced out ofthe cavity and onto the non-casting faces of the mold. This problemtends to be minimized when the lens forming composition undergoes fast,uniform gelation. Typically, a fast uniform gelation of the lens formingcomposition may be achieved by manipulating the timing, intensities, anddistribution of the activating radiation. The above described mid-indexlens forming compositions, however, tend to gel quickly and uniformlyunder a variety of curing conditions, thus minimizing the problemscaused by dripping.

[0310] Another advantage of the above described mid-index lens formingcompositions is that the compositions tend to undergo uniform curingunder a variety of curing conditions. This uniform curing tends tominimize optical aberrations within the formed lens. This is especiallyevident during the formation of high plus power flattop lenses whichtend to exhibit optical distortions after the lens forming compositionis cured. It is believed that the activating radiation may be reflectedoff of the segment line and create local differences in the rate ofgelation in the regions of the lens forming composition that thereflected light reaches. The above described mid-index lens formingcompositions tend to show less optical distortions caused by variationsof the intensity of activating radiation throughout the composition.

[0311] Other advantages include drier edges and increased rigidity ofthe formed lens. An advantage of drier edges is that the contaminationof the optical faces of the lens by uncured or partially cured lensforming composition is minimized.

Methods of Forming Plastic Lenses

[0312] Plastic lenses may be formed by disposing a lens formingcomposition into the mold cavity of a mold assembly and irradiating themold assembly with activating light. Coating materials may be applied tothe mold members prior to filling the mold cavity with the lens formingcomposition. The lens may be treated in a post-cure unit after thelens-curing process is completed.

[0313] The operation of the above described system to provide plasticlenses involves a number of operations. These operations are preferablycoordinated by the controller 50, which has been described above. Afterpowering the system, an operator is preferably signaled by thecontroller to enter the prescription of the lens, the type of lens, andthe type of coating materials for the lens. Based on these inputtedvalues the controller will preferably indicate to the operator whichmolds and gaskets will be required to form the particular lens.

[0314] After obtaining the appropriate mold members the mold members arepreferably cleaned prior to loading with a lens forming composition. Theinner surface (i.e., casting surface) of the mold members may be cleanedon a spin coating unit 20 by spraying the mold members with a cleaningsolution while spinning the mold members. Examples of cleaning solutionsinclude methanol, ethanol, isopropyl alcohol, acetone, methyl ethylketone, or a water based detergent cleaner. Preferably, a cleaningsolution which includes isopropyl alcohol is used to clean the moldmembers. As the mold member is contacted with the cleaning solution,dust and dirt may be removed and transferred into the underlying dish115 of the curing unit. After a sufficient amount of cleaning solutionhas been applied the mold members may be dried by continued spinningwithout the application of cleaning solution.

[0315] In an embodiment, the inner surface, i.e., the casting face, ofthe front mold member may be coated with one or more hardcoat layersbefore the lens forming composition is placed within the mold cavity.Preferably, two hardcoat layers are used so that any imperfections, suchas pin holes in the first hardcoat layer, are covered by the secondhardcoat layer. The resulting double hardcoat layer is preferablyscratch resistant and protects the subsequently formed eyeglass lens towhich the double hardcoat layer adheres. The hardcoat layers arepreferably applied using a spin coating unit 20. The mold member ispreferably placed in the spin coating unit and the coating materialapplied to the mold while spinning at high speeds (e.g., between about900 to 1000 RPM). After a sufficient amount of coating material has beenapplied, the coating material may be cured by the activating lightsource disposed in the cover. The cover is preferably closed andactivating light is preferably applied to the mold member while the moldmember is spinning at relatively low speeds (e.g., between about 150 to250 RPM. Preferably control of the spinning and the application ofactivating light is performed by controller 50. Controller 50 ispreferably configured to prompt the operator to place the mold memberson the coating unit, apply the coating material to the mold member, andclose the cover to initiate curing of the coating material.

[0316] In an embodiment, the eyeglass lens that is formed may be coatedwith a hydrophobic layer, e.g. a hardcoat layer. The hydrophobic layerpreferably extends the life of the photochromic pigments near thesurfaces of the lens by preventing water and oxygen molecules fromdegrading the photochromic pigments.

[0317] In a preferred embodiment, both mold members may be coated with acured adhesion-promoting composition prior to placing the lens formingcomposition into the mold cavity. Providing the mold members with suchan adhesion-promoting composition is preferred to increase the adhesionbetween the casting surface of the mold and the lens formingcomposition. The adhesion-promoting composition thus reduces thepossibility of premature release of the lens from the mold. Further, itis believed that such a coating also provides an oxygen and moisturebarrier on the lens which serves to protect the photochromic pigmentsnear the surface of the lens from oxygen and moisture degradation. Yetfurther, the coating provides abrasion resistance, chemical resistance,and improved cosmetics to the finished lens.

[0318] In an embodiment, the casting face of the back mold member may becoated with a material that is capable of being tinted with dye prior tofilling the mold cavity with the lens forming composition. This tintablecoat preferably adheres to the lens forming composition so that dyes maylater be added to the resulting eyeglass lens for tinting the lens. Thetintable coat may be applied using the spin coating unit as describedabove.

[0319] The controller may prompt the user to obtain the appropriate lensforming composition. In one embodiment, the controller will inform theuser of which chemicals and the amounts of each chemical that isrequired to prepare the lens forming composition. Alternatively, thelens forming compositions may be preformed. In this case the controllermay indicate to the operator which of the preformed lens formingcompositions should be used.

[0320] In an embodiment, dyes may be added to the lens formingcomposition. It is believed that certain dyes may be used to attack andencapsulate ambient oxygen so that the oxygen may be inhibited fromreacting with free radicals formed during the curing process. Also, dyesmay be added to the composition to alter the color of an unactivatedphotochromic lens. For instance, a yellow color that sometimes resultsafter a lens is formed may be “hidden” if a blue-red or blue-pink dye ispresent in the lens forming composition. The unactivated color of aphotochromic lens may also be adjusted by the addition ofnon-photochromic pigments to the lens forming composition.

[0321] In a preferred technique for filling the lens molding cavity 382(see FIG. 11), the annular gasket 380 is placed on a concave or frontmold member 392 and a convex or back mold member 390 is moved intoplace. The annular gasket 380 is preferably pulled away from the edge ofthe back mold member 390 at the uppermost point and a lens formingcomposition is preferably injected into the lens molding cavity 382until a small amount of the lens forming composition is forced outaround the edge. The excess is then removed, preferably, by vacuum.Excess liquid that is not removed could spill over the face of the backmold member 390 and cause optical distortion in the finished lens.

[0322] The mold assembly, with a lens forming composition disposedwithin the mold cavity, is preferably placed within the lens curingunit. Curing of the lens forming composition is preferably initiated bythe controller after the lens curing unit door is closed. The curingconditions are preferably set by the controller based on theprescription and type of lens being formed.

[0323] After the curing cycle has been completed. The controllerpreferably prompts the user to remove the mold assembly from the lenscuring unit. In an embodiment, the cured lens may be removed from themold apparatus. The cured lens may be complete at this stage and readyfor use.

[0324] In another embodiment, the cured lens may require a post curetreatment. After the lens is removed from the mold apparatus the edgesof the lens may be dried and scraped to remove any uncured lens formingcomposition near the edges. The controller may prompt the user to placethe partially cured lens into a post-cure unit. After the lens has beenplaced within the post-cure unit the controller may apply light and/orheat to the lens to complete the curing of the lens. In an embodiment,partially cured lenses may be heated to about 115° C. while beingirradiated with activating light. This post-treatment may be applied forabout 5 minutes.

[0325] When casting a lens, particularly a positive lens that is thickin the center, cracking may be a problem. Addition polymerizationreactions, including photochemical addition polymerization reactions,may be exothermic. During the process, a large temperature gradient maybuild up and the resulting stress may cause the lens to crack. Yellowingof the finished lens may also be a problem. Yellowing tends to berelated to the monomer composition, the identity of the photoinitiator,and the concentration of the photoinitiator.

[0326] The formation of optical distortions usually occurs during theearly stages of the polymerization reaction during the transformation ofthe lens forming composition from the liquid to the gel state. Oncepatterns leading to optical distortions form they may be difficult toeliminate. When gelation occurs there typically is a rapid temperaturerise. The exothermic polymerization step causes a temperature increase,which in turn causes an increase in the rate of polymerization, whichcauses a further increase in temperature. If the heat exchange with thesurroundings is not sufficient to cool the lens, there will be a runawaysituation that leads to premature release, the appearance of thermallycaused striations and even breakage.

[0327] Accordingly, when continuous activating light is applied, it ispreferred that the reaction process be smooth and not too fast but nottoo slow. Heat is preferably not generated by the process so fast thatit may not be exchanged with the surroundings. The incident activatinglight intensity is preferably adjusted to allow the reaction to proceedat a desired rate. It is also preferred that the seal between theannular gasket 380 and the opposed mold members 378 be as complete aspossible.

[0328] Factors that have been found to lead to the production of lensesthat are free from optical distortions may be (1) achieving a good sealbetween the annular gasket 380 and the opposed mold members 378; (2)using mold members 378 having surfaces that are free from defects; (3)using a formulation having an appropriate type and concentration ofphotoinitiator that will produce a reasonable rate of temperature rise;and (4) using a homogeneous formulation. Preferably, these conditionsare optimized.

[0329] Premature release of the lens from the mold will result in anincompletely cured lens and the production of lens defects. Factors thatcontribute to premature release may be (1) a poorly assembled moldassembly 352; (2) the presence of air bubbles around the sample edges;(3) imperfection in gasket lip or mold edge; (4) inappropriateformulation; (5) uncontrolled temperature rise; and (6) high ornon-uniform shrinkage. Preferably, these conditions are minimized.

[0330] Premature release may also occur when the opposed mold members378 are held too rigidly by the annular gasket 380. Preferably, there issufficient flexibility in the annular gasket 380 to permit the opposedmold members 378 to follow the lens as it shrinks. Indeed, the lens mustbe allowed to shrink in diameter slightly as well as in thickness. Theuse of an annular gasket 380 that has a reduced degree of stickinesswith the lens during and after curing is therefore desirable.

[0331] Despite the above problems, the advantages offered by theradiation cured lens molding system clearly outweigh the disadvantages.The advantages of a radiation cured system include a significantreduction in energy requirements, curing time and other problemsnormally associated with conventional thermal systems.

[0332] 1. Method of Forming a Plastic Lens by Curing with ActivatingLight

[0333] In one embodiment, plastic lenses may be formed by disposing alens forming composition into the mold cavity of a mold assembly andirradiating the mold assembly with activating light. Coating materialsmay be applied to the mold members prior to filling the mold cavity withthe lens forming composition. The lens may be treated in a post-cureunit after the lens-curing process is completed.

[0334] The lens forming composition is preferably prepared according tothe following protocol. Appropriate amounts of HDDMA, TTEGDA, TMPTA andTRPGDA are mixed and stirred thoroughly, preferably with a glass rod.The acrylate/methacrylate mixture may then be passed through apurification column.

[0335] A suitable purification column may be disposed within a glasscolumn having a fitted glass disk above a Teflon stopcock and having atop reservoir with a capacity of approximately 500 ml and a body with adiameter of 22 mm and a length of about 47 cm. The column may beprepared by placing on the fitted glass disk approximately 35 g. ofactivated alumina (basic), available from ALFA Products, JohnsonMatthey, Danvers, Mass. in a 60 mesh form or from Aldrich in a 150 meshform. Approximately 10 g. of an inhibitor remover(hydroquinone/methylester remover) available as HR-4 from ScientificPolymer Products, Inc., Ontario, N.Y. then may be placed on top of thealumina and, finally, approximately 35 g. of activated alumina (basic)may be placed on top of the inhibitor remover.

[0336] Approximately 600 g. of the acrylate/methacrylate mixture maythen be added above the column packing. An overpressure of 2-3 psi maythen be applied to the top of the column resulting in a flow rate ofapproximately 30 to 38 grams per hour. Parafilm may be used to cover thejunction of the column tip and the receiving bottle to prevent theinfiltration of dust and water vapor. The acrylate/methacrylate mixture,preferably, may be received in a container that is opaque to activatinglight.

[0337] An appropriate amount of bisphenol A bis(allyl carbonate) maythen be added to the acrylate/methacrylate mixture to prepare the finalmonomer mixture.

[0338] An appropriate amount of a photoinitiator may then be added tothe final monomer mixture. The final monomer mixture, with or withoutphotoinitiator, may then be stored in a container that is opaque toactivating light.

[0339] An appropriate amount of a dye may also be added to the finalmonomer mixture, with or without photoinitiator.

[0340] After filling the mold cavity with the lens forming composition,the mold assembly is preferably irradiated with activating light. In oneembodiment, the lamps generate an intensity at the lamp surface ofapproximately 4.0 to 7.0 mW/cm² of ultraviolet light having wavelengthsbetween 300 and 400 nm, which light is very uniformly distributedwithout any sharp discontinuities throughout the reaction process. Suchbulbs are commercially available from Sylvania under the tradedesignation Sylvania Fluorescent (F15T8/2052) or Sylvania Fluorescent(F15T8/350BL/18″) GTE. Activating light having wavelengths between 300and 400 nm is preferred because the photoinitiators preferably absorbmost efficiently at this wavelength and the mold members 378,preferably, allow maximum transmission at this wavelength. It ispreferred that there be no sharp intensity gradients of activating lighteither horizontally or vertically through the lens composition duringthe curing process. Sharp intensity gradients through the lens may leadto defects in the finished lens.

[0341] If lenses are produced with continuous activating light withoutany mold cooling, the temperature of the mold-lens assembly may rise toabove 50° C. Low diopter lenses may be prepared in this fashion, buthigher plus or minus diopter lenses may fail. Certain lenses may be madeby controlling (e.g., cooling) the temperature of the lens materialduring cure with circulating uncooled fluid (i.e., fluid at ambienttemperatures). The ambient fluid in these systems is preferably directedtowards the mold members in the same manner as described above.Circulating ambient temperature fluid permits manufacture of a widerrange of prescriptions than manufacture of the lenses without any moldcooling at all.

[0342] Many polymerization factors may be interrelated. The idealtemperature of polymerization is typically related to the diopter andthickness of the lens being cast. Lower temperatures (below about 10°C.) are preferred to cast higher + or − diopter lenses when usingcontinuous activating light. These lower temperatures tend to permit anincrease in photoinitiator concentration, which in turn may speed up thereaction and lower curing time.

[0343] Preventing premature release when using continuous activatinglight may also be somewhat dependent upon the flow rates of coolingfluid, as well as its temperature. For instance, if the temperature ofthe cooling fluid is decreased it may also be possible to decrease theflowrate of cooling fluid. Similarly, the disadvantages of a highertemperature cooling fluid may be somewhat offset by higher flow rates ofcooling fluid.

[0344] In one embodiment the air flow rates for a dual distributorsystem (i.e., an air distributor above and below the lens composition)are about 1-30 standard cubic feet (“scf”) (about 0.028-0.850 standardcubic meters, “scm”) per minute per distributor, more preferably about4-20 scf (about 0.113-0.566 scm) per minute per distributor, and morepreferably still about 9-15 scf (about 0.255-0.423 scm) per minute perdistributor. “Standard conditions,” as used herein, means 60° F. (about15.5° C.) and one atmosphere pressure (about 101 kilopascals).

[0345] The thickness of the glass molds used to cast polymerized lensesmay affect the lenses produced. A thinner mold tends to allow moreefficient heat transfer between the polymerizing material and thecooling air, thus reducing the rate of premature release. In addition, athinner mold tends to exhibit a greater propensity to flex. A thinnermold tends to flex during the relatively rapid differential shrinkagebetween the thick and thin portions of a polymerized lens, againreducing the incidence of premature release. In one embodiment the firstor second mold members have a thickness less than about 5.0 mm,preferably about 1.0-5.0 mm, more preferably about 2.0-4.0 mm, and morestill about 2.5-3.5 mm.

[0346] “Front” mold or face means the mold or face whose surfaceultimately forms the surface of an eyeglass lens that is furthest fromthe eye of an eyeglass lens wearer. “Back” mold or face means the moldor face whose surface ultimately forms the surface of an eyeglass lensthat is closest to the eye of an eyeglass lens wearer.

[0347] In one embodiment, the lens forming material is preferably curedto form a solid lens at relatively low temperatures, relatively lowcontinuous activating light intensity, and relatively low photoinitiatorconcentrations. Lenses produced as such generally have a Shore Dhardness of about 60-78 (for preferred compositions) when cured forabout 15 minutes as described above. The hardness may be improved toabout 80-81 Shore D by postcure heating the lens in a conventional ovenfor about 10 minutes, as described above.

[0348] The activating light cured lenses may demonstrate excellentorganic solvent resistance to acetone, methyl ethyl ketone, andalcohols.

[0349] 2. Preparing Lenses of Various Powers By Altering the LensForming Conditions

[0350] It has been determined that in some embodiments the finishedpower of an activating light polymerized lens may be controlled bymanipulating the curing temperature of the lens forming composition. Forinstance, for an identical combination of mold members and gasket thefocusing power of the produced lens may be increased or decreased bychanging the intensity of activating light across the lens mold cavityor the faces of the opposed mold members.

[0351] As the lens forming material begins to cure, it passes through agel state, the pattern of which, within the mold assembly, leads to theproper distribution of internal stresses generated later in the curewhen the lens forming material begins to shrink. As the lens formingmaterial shrinks during the cure, the opposed mold members willpreferably flex as a result of the different amounts of shrinkagebetween the relatively thick and the relatively thin portions of thelens. When a negative lens, for example, is cured, the upper or backmold member will preferably flatten and the lower or front mold memberwill preferably steepen with most of the flexing occurring in the loweror front mold member. Conversely, with a positive lens, the upper orback mold member will preferably steepen and the lower or front moldmember will preferably flatten with most of the flexing occurring in theupper or back mold member.

[0352] By varying the intensity of the activating light between therelatively thin and the relatively thick portions of the lens in thelens forming cavity, it is possible to create more or less totalflexing. Those light conditions which result in less flexing will tendto minimize the possibility of premature release.

[0353] The initial curvature of the opposed mold members and the centerthickness of the lens produced may be used to compute the targeted powerof the lens. Herein, the “targeted power” of a lens is the power a lensmay have if the lens were to have a curvature and thicknesssubstantially identical to the mold cavity formed by the opposed moldmembers. The activating light conditions may be manipulated to alter thepower of the lens to be more or less than the targeted power.

[0354] By varying the amount of activating light reaching the lens moldthe polymerization rate, and therefore the temperature of the lensforming composition may be controlled. It has been determined that themaximum temperature reached by the lens forming composition duringand/or after activation by light may effect the final power of the lens.By allowing the lens forming composition to reach a temperature higherthan the typical temperatures described in previous embodiments, butless than the temperature at which the formed lens will crack, the powerof the lens may be decreased. Similarly, controlling the polymerizationsuch that the temperature of the lens forming composition remainssubstantially below the typical temperatures described in previousembodiments, but at a sufficient temperature such that a properly curedlens is formed, the power of the lens may be increased. Similarly,increasing the temperature of the lens forming composition during curingmay decrease the power of the resulting lens.

[0355] In an embodiment an ophthalmic eyeglass lens may be made from alens forming composition comprising a monomer and a photoinitiator, byirradiation of the lens forming composition with activating light. Thecomposition may optionally include one or more of: anultraviolet/visible light absorbing compound, a polymerizationinhibitor, a co-initiator, a hindered amine light stabilizer, and a dye.The activating light may include ultraviolet, actinic, visible orinfrared light. The lens forming composition may be treated withactivating light such that an eyeglass is formed that has a powersubstantially equal to the targeted power for a given mold cavity. Thepeak temperature of the lens forming process may be the maximumtemperature attained after the application of each pulse of activatinglight. As depicted in FIG. 40, each pulse of activating light may causethe lens forming composition to rise to a peak temperature.

[0356] After reaching this peak temperature the lens forming compositionmay begin to cool until the next application of activating light. If thepeak temperature of the lens forming composition is controlled such thatthe formed lens has a power substantially equal to the targeted power,the peak temperature is referred to as the “matching temperature”. Thematching temperature may be determined by performing a series ofexperiments using the same mold cavity. In these experiments the peaktemperature attained during the process is preferably varied. Bymeasuring the power of the lenses obtained through this experiment thematching temperature range may be determined.

[0357] When the temperature of the lens forming composition is allowedto rise above the matching temperature during treatment with activatinglight, the power of the lens may be substantially less than the targetedpower of the lens. Alternatively, when the temperature of the lensforming composition is allowed to remain below the matching temperature,the power of the lens may be substantially greater than the targetedpower of the lens. In this manner, a variety of lenses havingsubstantially different lens powers from the targeted power may beproduced from the same mold cavity.

[0358] When the lenses cured by the activating light are removed fromthe opposed mold members, they are typically under a stressed condition.It has been determined that the power of the lens may be brought to afinal resting power, by subjecting the lenses to a post-curing heattreatment to relieve the internal stresses developed during the cure andcause the curvature of the front and the back of the lens to shift.Typically, the lenses may be cured by the activating light in about10-30 minutes (preferably about 15 minutes). The post-curing heattreatment is preferably conducted at approximately 85-120° C. forapproximately 5-15 minutes. Preferably, the post-curing heat treatmentis conducted at 100-110° C. for approximately 10 minutes. Prior to thepost-cure, the lenses generally have a lower power than the finalresting power. The post-curing heat treatment reduces yellowing of thelens and reduces stress in the lens to alter the power thereof to afinal resting power.

[0359] In an embodiment an ophthalmic eyeglass lens may be made from alens forming composition comprising a monomer and a photoinitiator, byirradiation of the lens forming composition with activating light. Thecomposition may optionally include one or more of: anultraviolet/visible light absorbing compound, a polymerizationinhibitor, a co-initiator, a hindered amine light stabilizer, and a dye.The activating light may include ultraviolet, actinic, visible orinfrared light. The lens forming composition may be treated withactivating light such that an eyeglass is formed. The lens may be keptwithin the mold cavity formed by the mold members until the light hascompletely cured the lens forming composition. The minimum time which alens must remain in the mold cavity to produce a lens with the targetedpower, with respect to the mold cavity, is herein referred to as the“demolding time”. The demolding time may be determined by performing aseries of experiments using the same mold cavity. In these experimentsthe time that the lens is released from the mold cavity during theprocess is preferably varied. By measuring the power of the lensesobtained through these experiments the demolding time range may bedetermined.

[0360] When a formed lens is removed prior to the demolding time, thepower of the lens may be substantially greater than the targeted powerof the lens. By varying the demolding time a variety of lenses havingsubstantially greater lens powers from the targeted power may beproduced from the same mold cavity.

[0361] 3. Postcure with an Oxygen Barrier Enriched with Photoinitiator

[0362] In certain applications, all of the lens forming composition mayfail to completely cure by exposure to activating light when forming thelens. In particular, a portion of the lens forming composition proximatethe gasket often remains in a liquid state following formation of thelens. It is believed that the gaskets may be often somewhat permeable toair, and, as a result, oxygen permeates them and contacts the portionsof the lens forming material that are proximate the gasket. Since oxygentends to inhibit the polymerization process, portions of the lensforming composition proximate the gasket tend to remain uncured as thelens is formed.

[0363] Uncured lens forming composition proximate the gasket may be aproblem for several reasons. First, the liquid lens forming compositionleaves the edges of the cured lens in a somewhat sticky state, whichmakes the lenses more difficult to handle. Second, the liquid lensforming composition may be somewhat difficult to completely remove fromthe surface of the lens. Third, liquid lens forming composition may flowand at least partially coat the surface of lenses when such lenses areremoved from the molds. This coating may be difficult to remove andmakes application of scratch resistant coatings or tinting dyes moredifficult. This coating tends to interfere with the interaction ofscratch resistant coatings and tinting dyes with the cured lens surface.Fourth, if droplets of liquid lens forming material form, these dropletsmay later cure and form a ridge or bump on the surface of the lens,especially if the lens undergoes later postcure or scratch resistantcoating processes. As a result of the above problems, often lenses mustbe tediously cleaned or recast when liquid lens forming compositionremains after the lens is formed in an initial cure process.

[0364] The problems outlined above may be mitigated if less liquid lensforming composition remains proximate the gasket after the lens isformed. One method of lessening this “wet edge” problem relates toincreasing the amount of photoinitiator present in the lens formingcomposition (i.e., increasing the amount of photoinitiator in the lensforming composition above about 0.15 percent). Doing so, however, tendsto create other problems. Specifically, increased photoinitiator levelstend to cause exothermic heat to be released at a relatively high rateduring the reaction of the composition. Premature release and/or lenscracking tends to result. Thus it is believed that lower amounts ofphotoinitiator are preferred.

[0365] The wet edge problem has been addressed by a variety of methodsdescribed in U.S. Pat. No. 5,529,728 to Buazza et. al. Such methodsrelate to removing the gasket and applying either an oxygen barrier or aphotoinitiator enriched liquid to the exposed edge of the lens. The lensis preferably re-irradiated with sufficient activating light tocompletely dry the edge of the lens prior to demolding.

[0366] An embodiment relates to improving the methods described in U.S.Pat. No. 5,529,728 to Buazza et. al. This embodiment relates tocombining an oxygen barrier with a photoinitiator. Specifically, in oneembodiment an oxygen barrier 970 (e.g., a thin strip of polyethylenefilm or the like as shown in FIG. 12) is preferably embedded orimpregnated with a photoinitiator 972. The oxygen barrier is preferablywrapped around the edge of a cured lens which is still encased betweentwo molds (but with the gasket removed). While still “in the mold,” thelens is preferably exposed to activating light, thereby drying its edge.An improvement of this method over those previously disclosed is thatthere may be a significant reduction in the dosage of activating lightnecessary to bring the lens edge to dryness.

[0367] A plastic oxygen barrier film which includes a photoinitiator maybe made by: (a) immersing a plastic film in a solution comprising aphotoinitiator, (b) removing the plastic film from the solution, and (c)drying the plastic film. The solution may include an etching agent.Preferably a surface of the plastic film is etched prior to or whileimmersing the plastic film in the solution.

[0368] In one example, thin strips (e.g., about 10 mm wide) of highdensity polyethylene film (approximately 0.013 mm thick) may be soakedin a solution of 97% acetone and 3% Irgacure 184 (a photoinitiatorcommercially available from Ciba Geigy located in Farmingdale, N.J.) forabout five minutes. The polyethylene film may be obtained from TapeSolutions, Inc. (Nashville, Tenn.). In a more preferred embodiment, 0.5%BYK-300 (a flow agent commercially available from BYK Chemie located inWallingford, Conn.) may be included in the soaking solution. It isbelieved that xylene in the BYK-300 tends to etch the surface of thefilm and make the film more receptive to absorption of the Irgacure 184.In a still more preferred embodiment, the treated polyethylene stripsmay be dipped in acetone for about ten seconds to remove excess Irgacure184. Excess photoinitiator may be seen as a white powder which coats thestrips after drying. In either case, the strips are preferably allowedto air dry before applying them to the edge of the lens as describedabove.

[0369] In one alternate embodiment, a plastic eyeglass lens may be madeby the following steps: (1) placing a liquid polymerizable lens formingcomposition in a mold cavity defined by a gasket, a first mold member,and a second mold member, (2) directing first activating light raystoward at least one of the mold members to cure the lens formingcomposition so that it forms a lens with a back face, edges, and a frontface, and wherein a portion of the lens forming composition proximatethe edges of the lens is not fully cured; (3) removing the gasket toexpose the edges of the lens; (4) applying an oxygen barrier whichincludes a photoinitiator around the exposed edges of the lens such thatat least a portion of the oxygen barrier photoinitiator is proximatelens forming composition that is not fully cured; and (5) directingsecond activating light rays towards the lens such that at least aportion of the oxygen barrier photoinitiator initiates reaction of lensforming composition while the oxygen barrier substantially preventsoxygen from outside the oxygen barrier from contacting at least aportion of the lens forming composition. The first and second activatinglight rays may (a) be at the same or different wavelengths and/orintensities, (b) be continuous or pulsed, and (c) be from the same ordifferent light source.

[0370] A purpose of the steps 4-5 is to reduce the amount of uncuredliquid lens forming composition that is present when the lens isseparated from the molds and/or gasket. It has been found that reducingthe amount of liquid lens forming composition may be especiallyadvantageous if such reduction occurs before the molds are separatedfrom the cured lens. Separating the molds from the cured lens may causeuncured liquids to at least partially coat the lens faces. This coatingmay occur when uncured liquid lens forming composition gets swept overthe faces when the molds are separated from the lens. It is believedthat curing of the lens tends to create a vacuum between the lens andthe mold. Air may sweep over the mold faces to fill this vacuum when themolds are separated from the lens. This air tends to take liquid lensforming composition into the vacuum with it.

[0371] In step 4 above, an oxygen barrier which includes aphotoinitiator is preferably applied to the edges or sides of the lensafter the gasket is removed. Preferably, this oxygen barrier is appliedwhile the lens is still attached to the molds. In an alternateembodiment, this oxygen barrier is preferably applied to the edges orsides of the molds at the same time it is applied to the sides of thelens. In a preferred embodiment, the sides of the lenses are firstcleaned or wiped to remove at least a portion of the uncured liquid lensforming composition before the oxygen barrier is applied.

[0372] After the oxygen barrier is applied, second activating light raysmay be directed towards the lens. After the second activating light raysare directed toward the lens, at least a portion of the liquid lensforming composition that was not cured in the initial cure steps may becured. It is believed that the photoinitiator embedded in the oxygenbarrier facilitates faster and more complete curing of the uncured lensforming composition. As such, less second activating light rays may beemployed, thereby lessening the time and energy required in this step.Furthermore, lens quality tends to be enhanced since a lower applicationof the second activating light rays tends to reduce the potential forlens yellowing.

[0373] In a preferred embodiment, substantially all of the remainingliquid lens forming composition is cured after the second activatinglight rays are directed toward the lens. More preferably, the lens issubstantially dry after the second activating light is directed towardsthe lens.

[0374] After the second activating light is directed toward the lens,the lens may then be demolded. The lens may then be tinted. After thelens is demolded, a scratch resistant coating may be applied to thelens. In one embodiment, a scratch resistant coating is preferablyapplied to the demolded lens by applying a liquid scratch resistantcoating composition to a face of the lens and then applying activatinglight rays to this face to cure the liquid scratch resistant coating toa solid.

[0375] In an embodiment, the activating light for curing the scratchresistant coating is ultraviolet light. The intensity of the activatinglight applied to the face of the lens to cure the liquid scratchresistant coating composition to a solid is preferably about 150-300mW/cm² at a wavelength range of about 360-370 nm, and about 50-150mW/cm² at a wavelength range of about 250-260 nm. The lens may be heatedafter removal from the molds, or after application of a scratchresistant coating to the lens.

[0376] In a preferred embodiment, the above method may further includethe additional step of directing third activating light rays towards thelens before the oxygen barrier is applied. These third activating lightrays are preferably applied before the gasket is removed. Preferably,the second and third activating light rays are directed toward the backface of the lens (as stated above, the second and third activating lightrays are preferably applied while this lens is in the mold cavity). Thethird activating light rays are preferably about the same range ofintensity as the second activating light rays. The same apparatus may beused for both the second and third activating light rays.

[0377] In a preferred embodiment, the method described above alsoincludes the step of removing the oxygen barrier from the edges of thelens.

[0378] The second and third activating light rays may be repeatedlydirected towards the lens. For instance, these activating light rays maybe applied via a light assembly whereby the lens passes under a lightsource on a movable stand. The lens may be repeatedly passed under thelights. Repeated exposure of the lens to the activating light rays maybe more beneficial than one prolonged exposure.

[0379] Preferably the oxygen barrier includes a film, and morepreferably a plastic, flexible, and/or elastic film. In addition, theoxygen barrier is preferably at least partially transparent toactivating light so that activating light may penetrate the oxygenbarrier to cure any remaining liquid lens forming composition.Preferably, the oxygen barrier is stretchable and self-sealing. Thesefeatures make the film easier to apply. Preferably, the oxygen barrieris resistant to penetration by liquids, thus keeping any liquid lensforming composition in the mold assembly. Preferably, the oxygen barrierincludes a thermoplastic composition. It is anticipated that manydifferent oxygen barriers may be used (e.g., saran wrap, polyethylene,etc.). In one preferred embodiment, the film is “Parafilm M LaboratoryFilm” which is available from American National Can (Greenwich, Conn.,U.S.A.). The oxygen barrier may also include aluminum foil.

[0380] Preferably, the oxygen barrier is less than about 1.0 mm thick.More preferably, the oxygen barrier is 0.01 to 0.10 mm thick, and morepreferably still, the oxygen barrier is less than 0.025 mm thick. If theoxygen barrier is too thick, then it may not be readily stretchableand/or conformable, and it may not allow a sufficient amount of light topass through it. If the oxygen barrier is too thin, then it may tend totear.

[0381] In an alternate method, a lens may be cured between two moldmembers. The gasket may be removed and any remaining liquid lenscomposition may be removed. At this point a mold member may be appliedto a substantially solid conductive heat source. Heat may then beconductively applied to a face of the lens by (a) conductivelytransferring heat to a face of a mold member from the conductive heatsource, and (b) conductively transferring heat through such mold memberto the face of the lens. The oxygen barrier enriched with photoinitiatormay then be applied, and second activating light rays may be directedtowards the lens to cure the remaining lens forming composition.

[0382] 4. Applying Coating Materials to Lenses

[0383] In an embodiment coating apparatus 20 may be used to apply apre-coat to a lens before the hardcoat is applied. The pre-coat mayserve to increase the “wettability” of the surface to which the hardcoatis to be applied. A surfactant has been conventionally employed for thispurpose, however surfactants tend to affect the volatility and flowcharacteristics of lens coatings in an unfavorable manner. The pre-coatmay include acetone and/or BYK-300. Upon even distribution of thehardcoat onto a lens, the coating may be wiped hear the edges of thelens to prevent the formation of excessive flakes during curing.

[0384] 5. Curing by the Application of Pulsed Activating Light

[0385] A polymerizable lens forming composition may be placed in amold/gasket assembly and continuously exposed to appropriate levels ofactivating light to cure the composition to an optical lens. Theprogress of the curing reaction may be determined by monitoring theinternal temperature of the composition. The lens forming compositionmay be considered to pass through three stages as it is cured: (1)induction, (2) gel formation & exotherm, and (3) extinction. Thesestages are illustrated in FIG. 22 for a −0.75 -1.00 power lens cured bycontinuous application of activating light. FIG. 22 shows temperaturewithin the mold cavity as a function of time throughout a continuousradiation curing cycle.

[0386] The induction stage occurs at the beginning of the curing cycleand is typically characterized by a substantially steady temperature ofthe lens forming composition as it is irradiated with activating light(or falling temperature when the curing chamber temperature is belowthat of the composition). During the induction period, the lens formingcomposition remains in a liquid state as the photoinitiator breaks downand consumes inhibitor and dissolved oxygen present in the composition.As the inhibitor content and oxygen content of the composition fall,decomposing photoinitiator and the composition begin to form chains toproduce a pourable, “syrup-like” material.

[0387] As irradiation continues, the “syrup” proceeds to develop into asoft, non-pourable, viscous, gel. A noticeable quantity of heat willbegin to be generated during this soft gel stage. The optical quality ofthe lens may be affected at this point. Should there be any sharpdiscontinuities in the intensity of the activating light (for example, adrop of composition on the exterior of a mold which focuses light into aportion of the lens forming composition proximate the drop), a localdistortion will tend to be created in the gel structure, likely causingan aberration in the final product. The lens forming composition willpass through this very soft gel state and through a firm gel state tobecome a crystalline structure. When using OMB-91 lens formingcomposition, a haze tends to form momentarily during the transitionbetween the gel and crystalline stages. As the reaction continues andmore double bonds are consumed, the rate of reaction and the rate ofheat generated by the reaction will slow, which may cause the internaltemperature of the lens forming composition to pass through a maximum atthe point where the rate of heat generation exactly matches the heatremoval capacity of the system.

[0388] By the time the maximum temperature has been reached and the lensforming composition begins to cool, the lens will typically haveachieved a crystalline form and will tend to crack rather than crumbleif it is broken. The rate of conversion will slow dramatically and thelens may begin to cool even though some reaction still may be occurring.Irradiation may still be applied through this extinction phase.Generally, the curing cycle is assumed to be complete when thetemperature of the lens forming composition falls to a temperature nearits temperature at the beginning of exotherm (i.e., the point where thetemperature of the composition increased due to the heat released by thereaction).

[0389] The continuous irradiation method tends to work well forrelatively low mass lenses (up to about 20-25 grams, see, e.g., U.S.Pat. Nos. 5,364,256 and 5,415,816). As the amount of material beingcured increases, problems may be encountered. The total amount of heatgenerated during the exothermic phase is substantially proportional tothe mass of the lens forming material. During curing of relatively highmass lenses, a greater amount of heat is generated per a given time thanduring curing of lower mass lenses. The total mold/gasket surface areaavailable for heat transfer (e.g., heat removal from the lens formingcomposition), however, remains substantially constant. Thus, theinternal temperature of a relatively high mass of lens forming materialmay rise to a higher temperature more rapidly than typically occurs witha lower mass of lens forming material. For example, the internaltemperature of a low minus cast-to-finish lens typically will not exceedabout 100° F., whereas certain thicker semi-finished lens “blanks” mayattain temperatures greater than about 350° F. when continually exposedto radiation. The lens forming material tends to shrink as curingproceeds and the release of excessive heat during curing tends to reducethe adhesion between the mold and the lens forming material. Thesefactors may lead to persistent problems of premature release and/orcracking during the curing of lens forming material having a relativelyhigh mass.

[0390] An advantage of the present method is the production ofrelatively high-mass, semi-finished lens blanks and high powercast-to-finish lenses without the above-mentioned problems of prematurerelease and cracking. The methods described below allow even morecontrol over the process of curing ophthalmic lenses with activatinglight-initiated polymerization than previous methods. By interrupting ordecreasing the activating light at the proper time during the cycle, therate of heat generation and release may be controlled and the incidenceof premature release may be reduced. An embodiment relates to a methodof controlling the rate of reaction (and therefore the rate of heatgeneration) of an activating light-curable, lens forming material byapplying selected intermittent doses (e.g., pulses) of radiationfollowed by selected periods of decreased activating light or“darkness”. It is to be understood that in the description that follows,“darkness” refers to the absence of activating radiation, and notnecessarily the absence of visible light.

[0391] More particularly, an embodiment relates to: (a) an initialexposure period of the lens forming material to radiation (e.g.,continuous or pulsed radiation) extending through the induction period,(b) interrupting or decreasing the irradiation before the materialreaches a first temperature (e.g., the maximum temperature thecomposition could reach if irradiation were continued) and allowing thereaction to proceed to a second temperature lower than the firsttemperature, and (c) applying a sufficient number of alternating periodsof exposure and decreased activating light or darkness to the lensforming material to complete the cure while controlling the rate of heatgeneration and/or dissipation via manipulation of the timing andduration of the radiation, or the cooling in the curing chamber. FIG. 23shows the temperature within the mold cavity as a function of time forboth (a) continuous activating light exposure and (b) pulsed activatinglight exposure.

[0392] In the context of this application, a “gel” occurs when theliquid lens forming composition is cured to the extent that it becomessubstantially non-pourable, yet is still substantially deformable andsubstantially not crystallized.

[0393] In the following description, it is to be understood that theterm “first period” refers to the length of time of the initial exposureperiod where radiation (e.g., in pulses) is applied to the lens formingcomposition, preferably to form at least a portion of the compositioninto a gel. “First activating” rays or light refers to the radiationapplied to the lens forming composition during the initial exposureperiod. “Second activating” rays or light refers to the radiation thatis applied to the lens forming composition (e.g., in pulses) after thecomposition has been allowed to cool to the “third temperature”mentioned above. “Second period” refers to the duration of time thatsecond activating rays are directed to the lens forming composition.“Third period” refers to the duration of decreased activating light ordarkness that ensues after activating light has been delivered in thesecond period.

[0394] In an embodiment, the lens forming material is preferably placedin a mold cavity defined in part between a first mold member and asecond mold member. The first mold member and/or second mold member mayor may not be continuously cooled as the formation of the lens iscompleted during the second period and/or third period. One method ofremoving heat from the lens forming material is to continuously directair at a non-casting face of at least one of the mold members. It ispreferred that air be directed at both the first and second moldmembers. A cooler may be used to cool the temperature of the air to atemperature below ambient temperature, more preferably between about 0°C. and about 20° C., and more preferably still between about 3° C. andabout 15° C. Air may also be used to cool at least one of the moldmembers (in any of the manners described previously) during the firstperiod.

[0395] In an embodiment, the first period ends when at least a portionof the lens forming composition begins to increase in temperature orform a gel, and the first activating rays are decreased or removed(e.g., blocked) such that they cease to contact the first or second moldmembers. It is preferred that the first period be sufficient to allowthe lens forming material to gel in the mold cavity such that there issubstantially no liquid present (except small amounts proximate the edgeof the material). The interruption of irradiation prior to completegellation may in some circumstances produce optical distortions. It ispreferred that the length of the first period be selected to inhibit thelens forming composition from reaching a first temperature. The firsttemperature is preferably the maximum temperature that the lens formingcomposition could reach if it was irradiated under the system conditions(e.g., flow rate and temperature of any cooling air, wavelength andintensity of radiation) until the “exothermic potential” (i.e., abilityto evolve heat through reaction) of the composition was exhausted.

[0396] According to an embodiment, the reactions within the compositionare preferably allowed to proceed after the first activating rays areremoved until the composition reaches a second temperature. The secondtemperature is preferably less than the first temperature. The firsttemperature is preferably never reached by the composition. Thus, thecomposition is preferably prevented from achieving the first temperatureand then cooling to the second temperature. The composition ispreferably allowed to cool from the second temperature to the thirdtemperature. This cooling may occur “inactively” by allowing heat totransfer to the ambient surroundings, or at least one of the moldmembers may be cooled by any of the methods described above.

[0397] In an embodiment, the curing of the lens forming material may becompleted by directing second activating rays (e.g., in pulses) towardat least one of the mold members. The second activating rays may bedirected toward the mold member(s) for a second period that may bedetermined according to the rate of reaction of the lens formingcomposition. The change in temperature of the composition or a portionof the mold cavity, or the air in or exiting the chamber may be anindicator of the rate of reaction, and the second period may bedetermined accordingly. The second period may be varied such thatsubsequent pulses have a longer or shorter duration than previouspulses. The time between pulses (i.e., the third period) may also bevaried as a function of the temperature and/or reaction rate of thecomposition. To achieve a light pulse, (a) the power to a light sourcemay be turned on and then off, (b) a device may be used to alternatelytransmit and then block the passage of light to the lens formingcomposition, or (c) the light source and/or mold assembly may be movedto inhibit activating light from contacting the lens forming material.The second and/or third periods are preferably controlled to allow rapidformation of a lens while reducing the incidence of (a) prematurerelease of the lens from the first and/or second mold member and/or (b)cracking of the lens.

[0398] In an embodiment, the second period is preferably controlled toinhibit the temperature of the composition from exceeding the secondtemperature. The temperature of the lens forming composition maycontinue to increase after radiation is removed from the first and/orsecond mold members due to the exothermic nature of reactions occurringwithin the composition. The second period may be sufficiently brief suchthat the pulse of second activating rays is removed while thetemperature of the composition is below the second temperature, and thetemperature of the composition increases during the third period tobecome substantially equal to the second temperature at the point thatthe temperature of the composition begins to decrease.

[0399] In an embodiment, the third period extends until the temperatureof the composition becomes substantially equal to the third temperature.Once the temperature of the composition decreases to the thirdtemperature, a pulse of second activating rays may be delivered to thecomposition. In an embodiment, the second period remains constant, andthe third period is preferably controlled to maintain the temperature ofthe composition below the second temperature. The third period may beused to lower the temperature of the composition to a temperature thatis expected to cause the composition to reach but not exceed the secondtemperature after a pulse is delivered to the composition.

[0400] In an embodiment, a shutter system may be used to control theapplication of first and/or second activating rays to the lens formingmaterial. The shutter system preferably includes air-actuated shutterplates that may be inserted into the curing chamber to preventactivating light from reaching the lens forming material. Alternatively,the shutter system may include an LCD panel. Controller 50 may receivesignals from thermocouple(s) located inside the lens-curing chamber,proximate at least a portion the mold cavity, or located to sense thetemperature of air in or exiting the chamber, allowing the timeintervals in which the shutters are inserted and/or extracted to beadjusted as a function of a temperature within the curing chamber. Thethermocouple may be located at numerous positions proximate the moldcavity and/or casting chamber.

[0401] The wavelength and intensity of the second activating rays arepreferably substantially equal to those of the first activating rays. Itmay be desirable to vary the intensity and/or wavelength of theradiation (e.g., first or second activating rays). The particularwavelength and intensity of the radiation employed may vary amongembodiments according to such factors as the identity of the compositionand curing cycle variables.

[0402] Numerous curing cycles may be designed and employed. The designof an optimal cycle should include consideration of a number ofinteracting variables. Significant independent variables include: 1) themass of the sample of lens forming material, 2) the intensity of thelight applied to the material, 3) the physical characteristics of thelens forming material, and 4) the cooling efficiency of the system.Significant curing cycle (dependent) variables include: 1) the optimuminitial exposure time for induction and gelling, 2) the total cycletime, 3) the time period between pulses, 4) the duration of the pulses,and 5) the total exposure time.

[0403] Most of the experiments involving these methods were conductedusing below described OMB-91 monomer. The OMB-91 formulation andproperties are listed below. INGREDIENT WEIGHT PERCENT Sartomer SR 351(Trimethylolpropane 20.0 +/− 1.0  Triacrylate) Sartomer SR 268(Tetraethylene 21.0 +/− 1.0  Glycol Diacrylate) Sartomer SR 306(Tripropylene 32.0 +/− 1.0  Glycol Diacrylate) Sartomer SR 239 (1,6Hexanediol 10.0 +/− 1.0  Dimethacrylate) (Bisphenol A Bis (Ally1Carbonate)) 17.0 +/− 1.0  Irgacure 184 (1-Hydroxycyclohexyl  0.017 +/−0.0002 Phenyl Ketone) Methyl Benzoyl Formate  0.068 +/− 0.0007 MethylEster of Hydroquinone (“MeHQ”) 35 ppm +/− 10 ppm Thermoplast Blue P(9,10-Anthracenedione, 0.35 ppm +/− 0.1 ppm  1-hydroxy-4-((4-methylphenyl) Amino)

[0404] PROPERTY PROPOSED SPECIFICATION Appearance Clear Liquid Color(APHA) 50 maximum (Test Tube Test) Match Standard Acidity (ppm asAcrylic Acid) 100 maximum Refractive Index 1.4725 +/− 0.002 Density 1.08+/− 0.005 gm/cc. at 23° C. Viscosity @ 22.5 Degrees C. 27.0 +/− 2centipoise Solvent Weight (wt %) 0.1 Maximum Water (wt %) 0.1 MaximumMeHQ (from HPLC) 35 ppm +/− 10 ppm

[0405] It should be recognized that methods and systems disclosed couldbe applied to a large variety of radiation-curable, lens formingmaterials in addition to those mentioned herein. It should be understoodthat adjustments to curing cycle variables (particularly the initialexposure time) may be required even among lens forming compositions ofthe same type due to variations in inhibitor levels among batches of thelens forming compositions. In addition, changes in the heat removalcapacity of the system may require adjustments to the curing cyclevariables (e.g. duration of the cooling periods between radiationpulses). Changes in the cooling capacity of the system and/or changes incompositions of the lens forming material may require adjustments tocuring cycle variables as well.

[0406] Significant variables impacting the design of a pulsed curingcycle include (a) the mass of the material to be cured and (b) theintensity of the activating light applied to the material. If a sampleis initially overdosed with radiation, the reaction may progress too farand increase the likelihood of premature release and/or cracking. If asample is underdosed initially in a fixed (i.e., preset) curing cycle,subsequent exposures may cause too great a temperature rise later in thecycle, tending to cause premature release and/or cracking. Additionally,if the light intensity varies more than about +/−10% in a cycle that hasbeen designed for a fixed light intensity level and/or fixed mass oflens forming material, premature release and/or cracking may result.

[0407] An embodiment involves a curing cycle having two processes. Afirst process relates to forming a dry gel by continuously irradiating alens forming composition for a relatively long period. The material ispreferably cooled down to a lower temperature under darkness, after theirradiation is complete. A second process relates to controllablydischarging the remaining exothermic potential of the material byalternately exposing the material to relatively short periods ofirradiation and longer periods of decreased irradiation (e.g., darkcooling).

[0408] The behavior of the lens forming material during the secondprocess will depend upon the degree of reaction of the lens formingmaterial that has occurred during the first process. For a fixed curingcycle, it is preferable that the extent of reaction occurring in thefirst process consistently fall within a specified range. If theprogress of reaction is not controlled well, the incidence of crackingand/or premature release may rise. For a curing cycle involving acomposition having a constant level of inhibitor and initiator, theintensity of the radiation employed is the most likely source ofvariability in the level of cure attained in the first process.Generally, a fluctuation of +/−5% in the intensity tends to causeobservable differences in the cure level achieved in the first process.Light intensity variations of +/−10% may significantly reduce yieldrates.

[0409] The effect of various light intensities on the material beingcured depends upon whether the intensity is higher or lower than apreferred intensity for which the curing cycle was designed. FIG. 25shows temperature profiles for three embodiments in which differentlight levels were employed. If the light intensity to which the materialis exposed is higher than a preferred intensity, the overdosage maycause the reaction to proceed too far. In such a case, excessive heatmay be generated, increasing the possibility of cracking and/orpremature release during the first process of the curing cycle. Ifpremature release or cracking of the overdosed material does not occurin the first process, then subsequent pulses administered during thesecond process may create very little additional reaction.

[0410] If the light intensity is lower than a preferred intensity andthe lens forming material is underdosed, other problems may arise. Thematerial may not be driven to a sufficient level of cure in the firstprocess. Pulses applied during the second process may then causerelatively high amounts of reaction to occur, and the heat generated byreaction may be much greater than the heat removal capacity of thesystem. Thus the temperature of the lens forming material may tend toexcessively increase. Premature release may result. Otherwise,undercured lenses that continue generating heat after the end of thecycle may be produced.

[0411] The optimal initial radiation dose to apply to the lens formingmaterial may depend primarily upon its mass. The initial dose may alsobe a function of the light intensity and exposure time. A method fordesigning a curing cycle for a given mold/gasket/monomer combination mayinvolve selecting a fixed light intensity.

[0412] The methods disclosed may involve a wide range of lightintensities. Using a relatively low intensity may allow for the lengthof each cooling step to be decreased such that shorter and morecontrollable pulses are applied. Where a fluorescent lamp is employed,the use of a lower intensity may allow the use of lower power settings,thereby reducing the load on the lamp cooling system and extending thelife of the lamp. A disadvantage of using a relatively low lightintensity is that the initial exposure period may be somewhat longer.Relatively high intensity levels tend to provide shorter initialexposure times while placing more demand upon the lamp drivers and/orlamp cooling system, either of which tends to reduce the life of thelamp.

[0413] Once a light intensity is selected, the initial exposure time maybe determined. A convenient method of monitoring the reaction during thecycle involves fashioning a fine gauge thermocouple, positioning itinside the mold cavity, and connecting it to an appropriate dataacquisition system. A preferred thermocouple is Type J, 0.005 inchdiameter, Teflon-insulated wire available from Omega Engineering. Theinsulation is preferably stripped back about 30 to 50 mm and each wireis passed through the gasket wall via a fine bore hypodermic needle. Theneedle is preferably removed and the two wires may be twisted togetherto form a thermocouple junction inside the inner circumference of thegasket. The other ends of the leads may be attached to a miniatureconnector which may be plugged into a permanent thermocouple extensioncord leading to the data acquisition unit after the mold set is filled.

[0414] The data acquisition unit may be a Hydra 2625A Data Logger madeby John Fluke Mfg. Company. It is preferably connected to an IBMcompatible personal computer running Hydra Data Logger software. Thecomputer is preferably configured to display a trend plot as well asnumeric temperature readings on a monitor. The scan interval may be setto any convenient time period and a period of five or ten secondsusually provides good resolution.

[0415] The position of the thermocouple junction in the mold cavity mayaffect its reading and behavior through the cycle. When the junction islocated between the front and back molds, relatively high temperaturesmay be observed compared to the temperatures at or near the mold face.The distance from the edge of the cavity to the junction may affect bothabsolute temperature readings as well as the shape of the curing cycle'stemperature plot. The edges of the lens forming material may begin toincrease in temperature slightly later than other portions of thematerial. Later in the cycle, the lens forming material at the centermay be somewhat ahead of the material at the edge and will tend torespond little to the radiation pulses, whereas the material near theedge may tend to exhibit significant activity. When performingexperiments to develop curing cycles, it is preferred to insert twoprobes into the mold cavity, one near the center and one near the edge.The center probe should be relied upon early in the cycle and the edgeprobe should guide the later stages of the cycle.

[0416] Differing rates of reaction among various regions of the lensforming material may be achieved by applying a differential lightdistribution across the mold face(s). Tests have been performed where“minus type” light distributions have caused the edge of the lensforming material to begin reacting before the center of the material.The potential advantages of using light distributing filters to curehigh mass semi-finished lenses may be offset by non-uniformity of totallight transmission that tends to occur across large numbers of filters.

[0417] After the selection and/or configuration of (a) the radiationintensity, (b) the radiation-curable, lens forming material, (c) themold/gasket set, and (d) the data acquisition system, the optimuminitial exposure period may be determined. It is useful to expose asample of lens forming material to continuous radiation to obtain atemperature profile. This will provide an identifiable range of elapsedtime within which the optimal initial exposure time will fall. Twopoints of interest may be the time where the temperature rise in thesample is first detected (“T initial” or “Ti”), and the time where themaximum temperature of the sample is reached (“Tmax”). Also of interestis the actual maximum temperature, an indication of the “heat potential”of the sample under the system conditions (e.g., in the presence ofcooling).

[0418] As a general rule, the temperature of high mass lenses (i.e.,lenses greater than about 70 grams) should remain under about 200° F.and preferably between about 150° F. and about 180° F. Highertemperatures are typically associated with reduced lens yield rates dueto cracking and/or premature release. Generally, the lower mass lenses(i.e., lenses no greater than about 45 grams) should be kept under about150° F. and preferably between about 110° F. and about 140° F.

[0419] The first period may be selected according to the mass of thelens forming material. In an embodiment, the lens forming material has amass of between about 45 grams and about 70 grams and a selected secondtemperature between about 150° F. and about 200° F. According to anotherembodiment, the lens forming material has a mass no greater than about45 grams and a second temperature less than about 150° F. In yet anotherembodiment, the lens forming material has a mass of at least about 70grams, and a second temperature between about 170° F. and about 190° F.

[0420] An experiment may be performed in which the radiation is removedfrom the mold members slightly before one-half of the time between Tinitial and Tmax. The initial exposure time may be interactively reducedor increased according to the results of the above experiment insubsequent experiments to provide a Tmax in a preferred range. Thisprocedure may allow the determination of the optimal initial exposuretime for any given mold/gasket set and light intensity.

[0421] A qualitative summary of relationships among system variablesrelated to the above-described methods is shown in FIG. 24.

[0422] After the initial exposure period, a series of irradiationpulse/cooling steps may be performed to controllably discharge theremaining exothermic potential of the material and thus complete thecure. There may be at least two approaches to accomplish this secondprocess. The first involves applying a large number of very short pulsesand short cooling periods. The second approach involves applying a fewernumber of longer pulses with correspondingly longer cooling periods.Either of these two methods may produce a good product and manyacceptable cycles may exist between these extremes.

[0423] The described method relates to using pulsed application of lightto produce a large range (e.g., from −6 to +4 diopter) of lenses withoutrequiring refrigerated cooling fluid (e.g., cooled air). With properlight application, air at ambient may be used as a cooling fluid, thussignificantly reducing system costs.

[0424] The following general rules for the design of pulse/coolingcycles may be employed to allow rapid curing of a lens while inhibitingpremature release and/or cracking of the lens. The duration of thepulses preferably does not result in a temperature that exceeds themaximum temperature attained in the initial exposure period. The lengthof the cooling period may be determined by the length of time necessaryfor the internal temperature of the lens forming material to return tonear the temperature it had immediately before it received a pulse.Following these general rules during routine experimentation may permitproper curing cycles to be established for a broad range of lens formingmaterials, light intensity levels, and cooling conditions.

[0425] Preferably, light output is measured and controlled by varyingthe amount of power applied to the lights in response to changes inlight output. Specifically, a preferred embodiment includes a lightsensor mounted near the lights. This light sensor measures the amount oflight, and then a controller increases the power supplied to maintainthe first activating light rays as the intensity of the first activatinglight rays decreases during use, and vice versa. Preferably, the poweris varied by varying the electric frequency supplied to the lights.

[0426] In an embodiment, a medium pressure mercury vapor lamp is used tocure the lens forming material and the lens coating. This lamp and manyconventional light sources used for activating light curing may not berepeatedly turned on and off since a several minute warm-up period isgenerally required prior to operation. Mercury vapor light sources maybe idled at a lower power setting between exposure periods (i.e., secondperiods), however, the light source will still generate significant heatand consume electricity while at the lower power setting.

[0427] In an embodiment, air at ambient temperature may be used to coolthe lens forming composition. When a xenon flash lamp is used, thepulses of light generally have a duration of much less than about onesecond and considerably less radiative heat tends to be transferred tothe lens forming composition compared to curing methods employing otheractivating light sources. Thus, the reduced heat imparted to the lensforming composition may allow for air at ambient temperature to removesufficient heat of exotherm to substantially inhibit premature releaseand/or cracking of the lens.

[0428] In an embodiment, a xenon source is used to direct firstactivating light rays toward the first and second mold members to thepoint that a temperature increase is measured and/or the lens formingcomposition begins to or forms a gel. It is preferred that the gel isformed with less than 15 pulses of radiation, and more preferably withless than about 5 pulses. It is preferred that the gel is formed beforethe total time to which the composition has been exposed to the pulsesexceeds about {fraction (1/10)} or {fraction (1/100)} of a second.

[0429] In an embodiment, a reflecting device is preferably employed inconjunction with the xenon light source. The reflecting device ispositioned behind the flash source and preferably allows an evendistribution of activating light rays from the center of the compositionto the edge of the composition.

[0430] In an embodiment, a xenon light flash lamp is preferably used toapply a plurality of activating light pulses to the lens formingcomposition to cure it to an eyeglass lens in a time period of less than30 minutes, or more preferably, less than 20 or 15 minutes.

[0431] The use of a xenon light source also may allow the formation oflenses over a wider range of diopters. Higher power lenses exhibitgreatest thinnest to thickest region ratios, meaning that moreshrinkage-induced stress may be created, causing greater mold flexureand thus increased tendency for premature release. Higher power lensesalso possess thicker regions. Portions of lens forming material withinthese thicker regions may receive less light than regions closer to themold surfaces. Continuous irradiation lens forming techniques typicallyrequire the use of relatively low light intensities to control the heatgenerated during curing. The relatively low light intensities used tendsto result in a long, slow gellation period. Optical distortions tend tobe created when one portion of the lens is cured at a different ratethan another portion. Methods characterized by non-uniform curing aretypically poorly suited for the production of relatively high powerlenses, since the deeper regions (e.g., regions within a thick portionof a lens) tend to gel at a slower rate than regions closer to the moldsurfaces.

[0432] The relatively high intensity attainable with the xenon sourcemay allow deeper penetration into, and/or saturation of, the lensforming material, thereby allowing uniform curing of thicker lenses thanin conventional radiation-initiated curing. More uniform gelation mayoccur when the lens forming material is dosed with a high intensitypulse of activating light and then subjected to decreased activatinglight or darkness as the reaction proceeds without activating radiation.Lenses having a diopter of between about +5.0 and about −6.0 and greatermay be cured. It is believed that light distribution across the sampleis less critical when curing and especially when gelation is inducedwith relatively high intensity light. The lens forming material may becapable of absorbing an amount of energy per time that is below thatdelivered during a relatively high intensity pulse. The lens formingmaterial may be “oversaturated” with respect to the light delivered viaa high intensity flash source. In an embodiment, the xenon source ispreferably used to cure a lens having a diopter between about −4.0 andabout −6.0. In an embodiment, the xenon source is preferably used tocure a lens having a diopter between about +2.0 and about +4.0.

[0433] The methods disclosed herein allow curing of high-masssemi-finished lens blanks from the same material used to curecast-to-finish lenses. Both are considered to be “eyeglass lenses” forthe purposes of this patent. These methods may also be used to cure avariety of other lens forming materials. These methods have beensuccessfully used to make cast-to-finish lenses in addition tosemi-finished lenses.

[0434] 6. Improved Lens Curing Process

[0435] When casting an eyeglass lens with activating light, the gelationpattern of the lens forming composition may affect the resultant opticalquality of the lens. If there are localized discontinuities in the lightintensities received by the monomer contained in the casting cavityduring the early stages of the polymerization process, opticaldistortions may be seen in the finished product. Higher power lensesare, by definition, thicker in certain regions than relatively lowerpower lenses of the same diameter. The layers of a lens closest to themold faces of the casting cavity tend to receive a higher lightintensity than the deeper layers because the lens forming compositionabsorbs some of the incident light. This causes the onset ofpolymerization to be delayed in the deeper layers relative to the outerlayers, which may cause optical distortions in the finished product. Itis believed that concurrent with this differential curing rate, there isa difference in the rate of exothermic heat generation, specifically,the deeper regions will begin to generate heat after the outer regionsin the cavity have already cured and the effectiveness of the heatremoval may be impaired, contributing to optical waves and distortionsin the finished product. This phenomena is particularly observable inhigh powered positive lenses due to the magnification of such defects.

[0436] In an embodiment, the lens forming composition contained withinthe casting cavity is exposed to relatively high intensity activatinglight for a time period sufficient to initialize the reaction.Irradiation is preferably terminated before the polymerization of thelens forming composition proceeds far enough to generate a substantialamount of heat. This initial relatively high intensity dose preferablysubstantially uniformly gels the material within the casting cavity suchthat the difference in the rate of reaction between the inner and outerlayers of the lens being cured is preferably reduced, therebyeliminating the waves and distortions often encountered when usingcontinuous low intensity irradiation to initialize the reaction,particularly with high dioptric power positive lenses.

[0437] In an embodiment, the relatively high intensity dose ofactivating light is preferably applied to the lens forming compositionin the form of pulses. The pulses preferably have a duration of lessthan about 10 seconds, preferably less than about 5 seconds, and morepreferably less than about 3 seconds. The pulses preferably have anintensity of at least about 10 milliwatts/cm², more preferably at leastabout 100 milliwatts/cm², and more preferably still between about 150milliwatts/cm² and about 250 milliwatts/cm². It is preferred thatsubstantially all of the lens forming composition forms into a gel afterthe initial application of the relatively high intensity activatinglight. In an embodiment, no more than an insubstantial amount of heat isgenerated by exothermic reaction of the lens forming composition duringthe initial application of the relatively high intensity activatinglight.

[0438] Subsequent to this initial high intensity dose, a secondirradiation step may be performed in which the material contained withinthe casting cell is preferably irradiated for a relatively longer timeat a relatively lower intensity while cool fluid is directed at thenon-casting surface of at least one of the molds forming the cavity. Thecooling fluid preferably removes the exothermic heat generated by thepolymerization of the lens forming composition. If the intensity of theactivating light is too great during this second irradiation step, therate of heat generation will tend to be too rapid and the lens mayrelease prematurely from the casting face of the mold and/or crack.Similarly, should the rate of heat removal from the lens formingcomposition be too slow, the lens may release prematurely and/or crack.It is preferred that the mold/gasket assembly containing the lensforming composition be placed within the cooling environment as shortlyafter the initial dose of activating light as possible.

[0439] In an embodiment, the activating light applied to the lensforming composition during the second irradiation step is preferablyless than about 350 microwatts/cm², more preferably less than about 150microwatts/cm², and more preferably still between about 90microwatts/cm² and about 100 microwatts/cm². During the secondirradiation step, the activating light may be applied to the lensforming composition continuously or in pulses. A translucent highdensity polyethylene plate may be positioned between the activatinglight generator and at least one of the mold members to reduce theintensity of the activating light to within a preferred range.

[0440] In an embodiment relatively high intensity activating light ispreferably applied to the lens curing composition in a third irradiationstep to post-cure the lens subsequent to the second relatively lowintensity irradiation step. In the third irradiation step, pulses ofactivating light are preferably directed toward the lens formingcomposition, although the composition may be continuously irradiatedinstead. The pulses preferably have an intensity of at least about 10milliwatts/cm², more preferably at least about 100 milliwatts/cm², andmore preferably still between about 100 milliwatts/cm² and about 150milliwatts/cm².

[0441] Each of the above-mentioned irradiation steps is preferablyperformed by directing the activating light through each of the firstand second mold members. The eyeglass lens is preferably cured in atotal time of less than 30 minutes and is preferably free of cracks,striations, distortions, haziness, and yellowness.

[0442] It is believed that the above-described methods enable theproduction of whole lenses in prescription ranges beyond those currentlyattainable with continuous low intensity irradiation. The method may bepracticed in the curing of relatively high or low power lenses with areduced incidence of optical distortions in the finished lens ascompared to conventional methods. It is to be understood that theabove-described methods may be used independently or combined with themethods and apparatus of preferred embodiments described above in theprevious sections.

[0443] 7. Improved Scratch Resistant Lens Formation Process

[0444] The “in-mold” method involves forming a scratch resistant coatingover an eyeglass lens by placing the liquid coating in a mold andsubsequently curing it. The in-mold method may be advantageous to“out-of-mold” methods since the in-mold method exhibits less occurrencesof coating defects manifested as irregularities on the anterior surfaceof the coating. Using the in-mold method produces a scratch resistantcoating that replicates the topography and smoothness of the moldcasting face. However, a problem encountered when using conventionalin-mold scratch resistant coatings is that minute “pinholes” often formin the coating. It is believed that the pinholes may be caused by eithercontaminants on the mold, airborne particles falling on the coatingbefore it is cured, or bubbles formed during the application of thecoating which burst afterwards. The formation of such pinholes isespecially prevalent when using a flat-top bifocal mold, such as the onedepicted in FIG. 29. As illustrated, the segment line 454 of a bifocalsegment 452 below the main surface 456 of the mold reduces thesmoothness of the casting face. When a coating is spin-coated over themold face, this indentation may become an obstacle to the even flow ofthe casting face. The pinhole defects may be a problem in tinted lensesbecause the dye used to tint a lens may penetrate through the pinholes,resulting in a tiny speck of dye visible in the lens.

[0445] According to an embodiment, a first coating composition (i.e., apolymerizable “primer” material) is preferably passed through a filterand then placed within a mold member having a casting face and anon-casting face. The first coating composition preferably contains aphotoinitiator to make it curable upon exposure to activating light. Themold member may then be spun so that the first composition becomesdistributed over the casting face. The mold member may be rotated abouta substantially vertical axis at a speed between about 750 and about1500 revolutions per minute, preferably between about 800 and about 1000revolutions per minute, more preferably at about 900 revolutions perminute. Further, a dispensing device may be used to direct an additionalamount of the first composition onto the casting face while the moldmember is spinning. The dispensing device preferably moves from thecenter of the mold member to an edge of the mold member so that theadditional amount is preferably directed along a radius of the moldmember. Activating light is preferably directed at the mold member tocure at least a portion of the first composition.

[0446] A second coating composition may then be placed upon the firstcomposition in the mold member. The second coating is also preferablycurable when exposed to activating light because it contains aphotoinitiator. The mold member is preferably spun to distribute thesecond coating composition over the cured portion of the first coatingcomposition. The mold member may also be spun simultaneously whileadding the second composition to the mold member. Activating light isthen preferably directed at the mold member to simultaneously cure atleast a portion of the second coating composition and form a transparentcombination coat having both coating compositions. The combination coatis preferably a substantially scratch-resistant coating. The mold membermay then be assembled with a second mold member by positioning a gasketbetween the members to seal them. Therefore, a mold having a cavityshared by the original two mold members is formed. An edge of the gasketmay be displaced to insert a lens-forming composition into the cavity.The combination coat and the lens-forming material preferably adherewell to each other. This lens-forming composition preferably comprises aphotoinitiator and is preferably cured using activating light. Air whichpreferably has a temperature below ambient temperature may be directedtoward a non-casting face of the second mold member to cool thelens-forming composition while it is being cured.

[0447] The primer coat preferably comprises a mixture of high viscositymonomers, a low viscosity, low flashpoint organic solvent, and asuitable photoinitiator system. The solvent may make up more than about80% of the mixture, preferably about 93% to 96%. This mixture preferablyhas low viscosity and preferably covers any surface irregularity duringthe spin application, for example the segment line of a flat-top bifocalmold. The low flashpoint solvent preferably evaporates off relativelyquickly, leaving a thin layer of high viscosity monomer, containingphotoinitiator, which coats the casting face of the mold. The curedprimer coat is preferably soft to allow it to adhere well to the glassmold face. Since the primer coat is soft, it may not possess scratchresistant characteristics. However, applying a high scratch resistancehard coating (i.e., the second coating composition) to the primer coatpreferably results in a scratch resistant combination coat. The hardcoat preferably contains a solvent which evaporates when the mold memberis rotated to distribute the hard coating over the primer coat.

[0448] In general, the ideal primer material preferably possesses thefollowing characteristics: exhibits chemical stability at normal storageconditions (e.g., at room temperature and in the absence of activatinglight); flows well on an irregular surface, especially over a flat-topbifocal segment; when cured with a specified activating light dose,leaves a crack-free coating, with a high double bond conversion(approximately greater than 80%); maintains adhesion with the mold facethrough the lens forming curing cycle, especially the segment part ofthe flat-top bifocal mold; and is chemically compatible with the hardcoat that is subsequently applied on top of it (e.g., forms an opticallyclear combination coat). Even though pinhole defects may be present ineither the primer coat or the hard coat, it is highly unlikely thatdefects in one coat would coincide with defects of another coat. Eachcoat preferably covers the holes of the other coat, resulting in lesspinholes in the combination coat. Thus, the finished in-mold coated lensmay be tinted using dye without problems created by pinholes. It is alsopreferably free of cracks, yellowness, haziness, and distortions.

[0449] In an embodiment, the gasket between the fast mold member and thesecond mold member may be removed after a portion of the lens-formingmaterial has been cured. The removal of the gasket preferably exposes anedge of the lens. An oxygen barrier having a photoinitiator may beplaced around the exposed edge of the lens, wherein the oxygen barrierphotoinitiator is preferably near an uncured portion of the lens-formingcomposition. Additional activating light rays may then be directedtowards the lens to cause at least a portion of the oxygen barrierphotoinitiator to initiate reaction of the lens-forming material. Theoxygen barrier preferably prevents oxygen from contacting at least aportion of the lens forming composition during exposure of the lens tothe activating rays.

[0450] According to one embodiment, a substantially solid conductiveheat source is preferably applied to one of the mold members. Heat maybe conductively transferred from the heat source to a face of the moldmember. Further, the heat may be conductively transferred through themold member to the face of the lens.

[0451] 8. Method for Forming a Plastic Lens ContainingUltraviolet/Visible Light Absorbing Compounds

[0452] Materials (hereinafter referred to as “ultraviolet/visible lightabsorbing compounds”) that absorb various degrees of ultraviolet/visiblelight may be used in an eyeglass lens to inhibit ultraviolet/visiblelight from being transmitted through the eyeglass lens. Such an eyeglasslens advantageously inhibits ultraviolet/visible light from beingtransmitted to the eye of a user wearing the lens. Curing of an eyeglasslens using activating light to initiate the polymerization of a lensforming composition generally requires that the composition exhibit ahigh degree of activating light transmissibility so that the activatingradiation may penetrate to the deeper regions of the lens cavity.Otherwise the resulting cast lens may possess optical aberrations anddistortions. The cast lens may also contain layers of cured material inthe regions closest to the transparent mold faces, sandwiching innerlayers which may be either incompletely cured, gelled, barely gelled, oreven liquid. Often, when even small amounts of ultraviolet/visible lightabsorbing compounds of the types well known in the art are added to anormally activating light curable lens forming composition,substantially the entire amount of lens forming composition containedwithin the lens cavity may remain liquid in the presence of activatingradiation.

[0453] Photochromic pigments which have utility for photochromiceyeglass lenses absorb ultraviolet/visible light strongly and changefrom an unactivated state to an activated state when exposed toultraviolet/visible light. The presence of photochromic pigments, aswell as other ultraviolet/visible light absorbing compounds within alens forming composition, generally does not permit enough activatingradiation to penetrate into the depths of the lens cavity sufficient tocause photoinitiators to break down and initiate polymerization of thelens forming composition. Thus, it may be difficult to cure a lensforming composition containing ultraviolet/visible light absorbingcompounds using activating light. It is therefore desirable to provide amethod for using activating light to initiate polymerization of aneyeglass lens forming monomer which contains ultraviolet/visible lightabsorbing compounds, in spite of the high activating light absorptioncharacteristics of the ultraviolet/visible light absorbing compounds.Examples of such ultraviolet/visible light absorbing compounds otherthan photochromic pigments are fixed dyes and colorless additives.

[0454] In an embodiment, an ophthalmic eyeglass lens may be made from alens forming composition comprising a monomer, an ultraviolet/visiblelight absorbing compound, an photoinitiator, and a co-initiator.Examples of these compounds are listed in the section “Lens FormingCompositions Including Ultraviolet Visible Light Absorbing Materials”.The lens forming composition, in liquid form, is preferably placed in amold cavity defined by a first mold member and a second mold member. Itis believed that activating light, which is directed toward the moldmembers to activate the photoinitiator, causes the photoinitiator toform a polymer chain radical. The polymer chain radical preferablyreacts with the co-initiator more readily than with the monomer. Theco-initiator may react with a fragment or an active species of eitherthe photoinitiator or the polymer chain radical to produce a monomerinitiating species in the regions of the lens cavity where the level ofactivating light is either relatively low or not present.

[0455] The co-initiator is preferably activated only in the presence ofthe photoinitiator. Further, without the co-initiator, thephotoinitiator may exclusively be activated near the surface of the lensforming composition but not within the middle portion of thecomposition. Therefore, using a suitable photoinitiator combined with aco-initiator permits polymerization of the lens forming composition toproceed through the depths of the lens cavity. A cured, clear,aberration free lens is preferably formed in less than about 30 minutes,more preferably in less than about 10 minutes. The lens, when exposed toultraviolet/visible light preferably inhibits at least a portion of theultraviolet/visible light from being transmitted through the lens thatis preferably formed. A lens that permits no ultraviolet light frompassing through the lens (at least with respect to certain ultravioletwavelengths) is more preferred.

[0456] The identity of the major polymerizable components of the lensforming composition tends to affect the optimal curing process. It isanticipated that the identity of the ultraviolet/visible light absorbingcompound present in the monomer or blend of monomers may affect theoptimal photoinitiator/co-initiator system used as well as the optimalcuring process used to initiate polymerization. Also, varying theidentities or the proportions of the monomer(s) in the lens formingcomposition may require adjustments to various production processvariables including, but not limited to, exposure times, exposureintensities, cooling times and temperatures, activating light andthermal postcure procedures and the like. For example, compositionscomprising relatively slow reacting monomers, such as bisphenol A bisallyl carbonate or hexanediol dimethacrylate, or compositions comprisingrelatively higher proportions of such monomers may require either longerexposure times, higher intensities, or both. It is postulated thatincreasing the amount of either fast reacting monomer or the initiatorlevels present in a system will require reduced exposure times, morerigidly controlled light doses, and more efficient exothermic heatremoval.

[0457] Exothermic reactions may occur during the curing process of thelens forming composition. The thicker portions of the lens formingcomposition may generate more heat than the thinner portions of thecomposition as a result of the exothermic reactions taking place. It isbelieved that the speed of reaction in the thicker sections is slowerthan in the thinner sections. Thus, in a positive lens a “donut effect”may occur in which the relatively thin outer portion of the lens formingcomposition reaches its fully cured state before the relatively thickinner portion of the lens forming composition. Conversely, in a negativelens the relatively thin inner portion of the lens forming compositionmay reach its fully cured state before the relatively thick outerportion of the lens forming composition.

[0458] After the lens forming composition is preferably loaded into amold assembly, the mold assembly is preferably irradiated withactivating light at an appropriate intensity and duration. Typically,the intensity and duration of activating light required to produce alens containing ultraviolet/visible light absorbers is preferablysignificantly higher than the intensity and duration of light requiredfor forming non-ultraviolet/visible light absorbing lenses. The moldassembly may also require multiple doses for curing. This may require adifferent apparatus and/or setup from that used to form non-UV absorbinglenses.

[0459] In one embodiment, an apparatus may be capable of forming clear,colored, or photochromic lenses without significantly altering theapparatus. In order to achieve this the lens forming composition willpreferably include ultraviolet/visible light absorbers. By placingultraviolet/visible light absorbers in a clear non-photochromic lensforming composition, a clear lens may be obtained under similarconditions to those used for colored and photochromic lenses. Thus, theaddition of ultraviolet/visible light absorbers to a non-photochromiclens forming composition, allows both photochromic and non-photochromiclens forming compositions to be cured using the same apparatus andsimilar procedures. An added advantage, is that the produced clearlenses provide additional ultraviolet/visible light protection to theuser that may not be present in clear lenses formed withoutultraviolet/visible light absorbers. In this manner, plastic lenses maybe formed which exhibit many of the same properties as glass lenseshowever, the plastic lenses may be produced more rapidly, at lower cost,and have a weight significantly less than their glass counterparts.

[0460] 9. Actinic Light Initiated Polymerization Ultraviolet/VisibleLight Absorbing Compositions

[0461] Curing of an eyeglass lens using activating light to initiate thepolymerization of a lens forming composition generally requires that thecomposition exhibit a high degree of activating light transmissibilityso that the activating light may penetrate to the deeper regions of thelens cavity. Otherwise the resulting cast lens may possess opticalaberrations and distortions. The cast lens may also contain layers ofcured material in the regions closest to the transparent mold faces,sandwiching inner layers which may be either incompletely cured, gelled,barely gelled, or even liquid. Often, when even small amounts ofactivating light absorbing compounds have been added to a normallycurable lens forming composition, substantially the entire amount oflens forming composition contained within the lens cavity may remainliquid in the presence of activating light.

[0462] Photochromic pigments that have utility for photochromic eyeglasslenses typically absorb activating light strongly and change from aninactivated state to an activated state when exposed to activatinglight. The presence of photochromic pigments, as well as otheractivating light absorbing compounds within a lens forming composition,generally does not permit enough activating radiation to penetrate intothe depths of the lens cavity sufficient to cause photoinitiators tobreak down and initiate polymerization of the lens forming composition.Examples of such activating light absorbing compounds other thanphotochromic pigments are fixed dyes and colorless additives.

[0463] It is therefore difficult to cure a lens forming compositioncontaining activating light absorbing compounds using activating light.One solution to this problem involves the use of a co-initiator. Byusing a co-initiator, activating light may be used to initiate thepolymerization reaction. It is believed that activating light that isdirected toward the mold members may cause the photoinitiator to form apolymer chain radical. The polymer chain radical preferably reacts withthe co-initiator more readily than with the monomer. The co-initiatormay react with a fragment or an active species of either thephotoinitiator or the polymer chain radical to produce a monomerinitiating species in the regions of the lens cavity where the level ofactivating light is either relatively low or not present. It istherefore desirable to provide a method for polymerizing an eyeglasslens forming composition that contains light absorbing compounds byusing activating light having a wavelength that is not absorbed by thelight absorbing compounds, thus avoiding the need for a co-initiator.

[0464] In an embodiment, an ophthalmic eyeglass lens may be made from alens forming composition comprising a monomer, a light absorbingcompound, and a photoinitiator, by irradiation of the lens formingcomposition with activating light. As used herein “activating light”means light that may effect a chemical change. Activating light mayinclude ultraviolet light, actinic light, visible light or infraredlight. Generally any wavelength of light capable of effecting a chemicalchange may be classified as activating. Chemical changes may bemanifested in a number of forms. A chemical change may include, but isnot limited to, any chemical reaction which causes a polymerization totake place. Preferably the chemical change causes the formation of ainitiator species within the lens forming composition, the initiatorspecies being capable of initiating a chemical polymerization reaction.

[0465] The lens forming composition, in liquid form, is preferablyplaced in a mold cavity defined by a first mold member and a second moldmember. It is believed that activating light, when directed toward andthrough the mold members to activate the photoinitiator, causes thephotoinitiator to form a polymer chain radical. The polymer chainradical may react with a fragment or an active species of eitherphotoinitiator or the polymer chain radical to produce a monomerinitiating species in other regions of the lens cavity.

[0466] The use of activating light of the appropriate wavelengthpreferably prevents the lens from darkening during the curing process.Herein, “darkening” means becoming at least partially non-transparent tothe incoming activating light such that the activating light may notsignificantly penetrate the lens forming composition. Photochromiccompounds may cause such darkening. Ultraviolet/visible light absorbingcompounds present in the lens forming composition may prevent activatinglight having a wavelength substantially below about 380 nm frompenetrating into the lens forming composition. When treated withactivating light containing light with wavelengths in the ultravioletregion, e.g. light with wavelengths below about 380 nm, theultraviolet/visible light absorbing compounds may darken, preventingfurther ultraviolet activating light from penetrating the lens formingcomposition. The darkening of the lens forming composition may alsoprevent non-ultraviolet activating light from penetrating thecomposition. This darkening effect may prevent activating light of anywavelength from initiating the polymerization reaction throughout thelens forming composition.

[0467] When the ultraviolet/visible light absorbing compounds absorb inthe ultraviolet region, activating light having a wavelength above about380 nm (e.g., actinic light) may be used to prevent the darkeningeffect. Because the wavelength of the activating light is substantiallyabove the wavelength at which the ultraviolet/visible light absorbingcompounds absorb, the darkening effect may be avoided. Additionally,activating light with a wavelength above about 380 nm may be used toinitiate the polymerization of the lens forming material. By the use ofsuch activating light an eyeglass lens containing ultraviolet/visiblelight absorbing compounds may, in some circumstances, be formed withoutthe use of a co-initiator.

[0468] In an embodiment, the above-described lens forming composition,where the ultraviolet/visible light absorbing compound absorbs,predominantly, ultraviolet light, may be treated with activating lighthaving a wavelength above about 380 nm to activate the photoinitiator.Preferably, activating light having a wavelength substantially betweenabout 380 nm to 490 nm is used. By using activating light above about380 nm the darkening effect caused by the ultraviolet/visible lightabsorbing compounds may be avoided. The activating light may penetrateinto the lens forming composition, initiating the polymerizationreaction throughout the composition. A filter which blocks light havinga wavelength that is substantially below about 380 nm may be used toprevent the ultraviolet/visible light absorbing compounds fromdarkening.

[0469] The use of activating light permits polymerization of the lensforming composition to proceed through the depths of the lens cavity. Acured, clear, aberration free lens is preferably formed in less thanabout 30-60 minutes, more preferably in less than about 20 minutes. Asused herein a “clear lens” means a lens that transmits visible lightwithout scattering so that objects beyond the lens may be seen clearly.As used herein “aberration” means the failure of a lens to producepoint-to-point correspondence between an object and its image. The lens,when exposed to ultraviolet/visible light, preferably inhibits at leasta portion of the ultraviolet/visible light from being transmittedthrough the lens. In this manner the eye may be protected from certainlight. A lens that permits no ultraviolet/visible light from passingthrough the lens (at least with respect to certain wavelengths) is morepreferred.

[0470] In an embodiment, the lens forming composition that contains anultraviolet/visible light absorbing compound may be cured with anactivating light. Preferably, the activating light has a wavelengthsubstantially above about 380 mn. The lens forming composition may becured by exposing the composition to activating light multiple times.Alternatively, the lens forming composition may be cured by exposing thecomposition to a plurality of activating light pulses, at least one ofthe pulses having a duration of less than about one second (morepreferably less than about 0.1 seconds, and more preferably between 0.1and 0.001 seconds). Preferably, all activating light directed toward themold members is at a wavelength between about 380 nm to 490 nm. Thepreviously described embodiments which describe various methods andcompositions for forming eyeglass lenses may also be utilized to formthe eyeglass lens hereof, by replacing the ultraviolet light in theseexamples with activating light having a wavelength substantially greaterthan about 380 nm.

[0471] In an embodiment, the activating light may be generated from afluorescent lamp. The fluorescent lamp is preferably used to directactivating light rays toward at least one of the mold members. At leastone and preferably two fluorescent light sources, with strong emissionspectra in the 380 to 490 nm region may be used. When two light sourcesare used, they are preferably positioned on opposite sides of the moldcavity. A fluorescent lamp emitting activating light with the describedwavelengths is commercially available from Philips Electronics as modelTLD-15W/03.

[0472] Preferably, three or four fluorescent lamps may be positioned toprovide substantially uniform radiation over the entire surface of themold assembly to be cured. The activating light source may be turned onand off quickly between exposures. A flasher ballast may be used forthis function. A flasher ballast may operate in a standby mode wherein alow current is supplied to the lamp filaments to keep the filaments warmand thereby reduce the strike time of the lamp. Such a ballast iscommercially available from Magnatek, Inc of Bridgeport, Conn.Alternately, the light source may employ a shutter system to block thelight between doses. This shutter system is preferably controlled by amicro-processor based control system in order to provide the necessarydoses of light. A feedback loop may be used to control the lightintensity so that intensity fluctuations due to environmental variables(e.g. lamp temperature) and lamp aging may be minimized. A light sensormay be incorporated into the control system to minimize variances indose for a given exposure time.

[0473] The identity of the major polymerizable components of the lensforming composition tends to affect the optimal curing process. It isanticipated that the identity of the light absorbing compound present inthe monomer or blend of monomers may affect the optimal photoinitiatorsystem used as well as the optimal curing process used to initiatepolymerization. Also, varying the identities or the proportions of themonomer(s) in the lens forming composition may require adjustments tovarious production process variables including, but not limited to,exposure times, exposure intensities, cooling times and temperatures,postcure procedures and the like. For example, compositions includingrelatively slow reacting monomers, such as bisphenol A bis allylcarbonate or hexanediol dimethacrylate, or compositions includingrelatively higher proportions of such monomers may require either longerexposure times, higher intensities, or both. It is postulated thatincreasing the amount of either fast reacting monomer or the initiatorlevels present in a system will require reduced exposure times, morerigidly controlled light doses, and more efficient exothermic heatremoval.

[0474] Preferably, the monomers selected as components of the lensforming composition are capable of dissolving the light absorbingcompounds added to them. As used herein “dissolving” means beingsubstantially homogeneously mixed. For example, monomers may be selectedfrom a group including polyether (allyl carbonate) monomers,multi-functional acrylate monomers, and multi-functional methacrylicmonomers for use in an ultraviolet/visible light absorbing lens formingcomposition.

[0475] In an embodiment, the mixture of monomers, previously describedas PRO-629, may be blended together before addition of other componentsrequired to make the lens forming composition. This blend of monomers ispreferably used as the basis for a lens forming composition to whichultraviolet/visible light absorbing compounds are added.

[0476] A polymerization inhibitor may be added to the monomer mixture atrelatively low levels to inhibit polymerization of the monomer atinappropriate times (e.g., during storage). Preferably about 0 to 50 ppmof monomethylether hydroquinone (MEHQ) are added to the monomer mixture.It is also preferred that the acidity of the monomer mixture be as lowas possible. Preferably less than about 100 ppm residual acrylic acidexists in the mixture. It is also preferred that the water content ofthe monomer mixture be relatively low, preferably less than about 0.15percent.

[0477] Photoinitiators which have utility in the present method havebeen described in previous embodiments. Ultraviolet/visible lightabsorbing compounds which may be added to a normally ultraviolet/visiblelight transmissible lens forming composition have also been described inprevious embodiments. The quantity of photochromic pigments present inthe lens forming composition is preferably sufficient to provideobservable photochromic effect. The amount of photochromic pigmentspresent in the lens forming composition may widely range from about 1ppm by weight to 1-5% by weight. In preferred compositions, thephotochromic pigments are present in ranges from about 30 ppm to 2000ppm. In the more preferred compositions, the photochromic pigments arepresent in ranges from about 150 ppm to 1000 ppm. The concentration maybe adjusted depending upon the thickness of the lens being produced toobtain optimal visible light absorption characteristics.

[0478] In another embodiment co-initiators may be added to the lensforming composition. As described previously, such compositions may aidthe polymerization of the lens forming composition by interacting withthe photoinitiator such that the composition polymerizes in asubstantially uniform manner. It is anticipated that the optimal amountof the initiators is where the total amount of both initiators areminimized subject to the constraint of complete polymerization andproduction of a rigid, aberration free lens. The relative proportions ofthe photoinitiator to the co-initiator may be optimized byexperimentation. For example, an ultraviolet/visible light absorptivelens forming composition that includes a photoinitiator with noco-initiator may be cured. If waves and distortions are observed in theresulting lens, a co-initiator may then be added to the lens formingcomposition by increasing amounts until a lens having the best opticalproperties is formed. It is anticipated that excess co-initiator in thelens forming composition should be avoided to inhibit problems of toorapid polymerization, yellowing of the lens, and migration of residual,unreacted co-initiator to the surface of the finished lens.

[0479] In an embodiment, hindered amine light stabilizers may be addedto the lens forming composition. It is believed that these materials actto reduce the rate of degradation of the cured polymer caused byexposure to ultraviolet light by deactivating harmful polymer radicals.These compounds may be effective in terminating oxygen and carbon freeradicals, and thus interfering with the different stages ofauto-oxidation and photo-degradation. Preferably, more than one monomerand more than one initiator are used in a lens forming composition toensure that the initial polymerization of the lens forming compositionwith activating light does not occur over too short a period of time.The use of such a lens forming composition may allow greater controlover the gel formation, resulting in better control of the opticalquality of the lens.

[0480] An eyeglass lens formed using the lens forming compositionsdescribed may be applicable for use as a prescription lens and for anon-prescription lens. Particularly, such a lens may be used insunglasses. Advantageously, photochromic sunglass lenses would remainlight enough in color to allow a user to see through them clearly whileat the same time prohibiting ultraviolet/visible light from passingthrough the lenses. In one embodiment, a background dye may be added tothe photochromic lens to make the lens appear to be a dark shade ofcolor at all times like typical sunglasses.

SPECIFIC EXAMPLES

[0481] The following examples are included to demonstrate embodiments ofthe invention. Those of skill in the art, in light of the presentdisclosure, should appreciate that many changes may be made in thespecific examples that are disclosed and still obtain a like or similarresult without departing from the spirit and scope of the invention.

Example 1 Formation of a Plastic Lens by Curing With Activating Light

[0482] Formulation:   17% Bisphenol A bis(allyl carbonate)   10% 1,6Hexanediol dimethacrylate   20% Trimethylolpropane triacrylate   21%Tetraethyleneglycol diacrylate   32% Tripropyleneglycol diacrylate0.012% 1 Hydroxycyclohexyl phenyl ketone 0.048 Methyl benzoylformate <10ppm Hydroquinone & Methylethylhydroquinone

[0483] Hydroquinone and Methylethylhydroquinone were stabilizers presentin some of the diacrylate and/or triacrylate compounds obtained fromSartomer. Preferably the amount of stabilizers is minimized since thestabilizers affect the rate and amount of curing. If larger amounts ofstabilizers are added, then generally larger amounts of photoinitiatorsmust also be added.

[0484] Light Condition:

[0485] mW/cm² measured at plane of sample with Spectroline DM 365N Meterfrom Spectronics Corp. (Westbury, N.Y.) Center Edge Top: 0.233 0.299Bottom: 0.217 0.248

[0486] AirFlow:

[0487] 9.6 standard cubic feet per minute (“CFM”) per manifold-19.2 CFMtotal on sample

[0488] Air Temperature:

[0489] 4.4 degrees Centigrade

[0490] Molds:

[0491] 80 mm diameter Corning #8092 glass Radius Thickness Concave:170.59 2.7 Convex: 62.17 5.4

[0492] Gasket:

[0493] General Electric SE6035 silicone rubber with a 3 mm thick laterallip dimension and a vertical lip dimension sufficient to provide aninitial cavity center thickness of 2.2 mm.

[0494] Filling:

[0495] The molds were cleaned and assembled into the gasket. Themold/gasket assembly was then temporarily positioned on a fixture whichheld the two molds pressed against the gasket lip with about 1 kg. ofpressure. The upper edge of the gasket was peeled back to allow about27.4 grams of the monomer blend to be charged into the cavity. The upperedge of the gasket was then eased back into place and the excess monomerwas vacuumed out with a small aspirating device. It is preferable toavoid having monomer drip onto the noncasting surface of the moldbecause a drop tends to cause the activating light to become locallyfocused and may cause an optical distortion in the final product.

[0496] Curing:

[0497] The sample was irradiated for fifteen minutes under the aboveconditions and removed from the lens curing unit The molds wereseparated from the cured lens by applying a sharp impact to the junctionof the lens and the convex mold. The sample was then postcured at 110°C. in the post-cure unit for an additional ten minutes, removed andallowed to cool to room temperature.

[0498] Results:

[0499] The resulting lens measured 72 mm in diameter, with a centralthickness of 2.0 mm, and an edge thickness of 9.2 mm. The focusing powermeasured ˜5.05 diopter. The lens was water clear (“water-white”), showednegligible haze, exhibited total visible light transmission of about94%, and gave good overall optics. The Shore D hardness was about 80.The sample withstood the impact of a 1 inch steel ball dropped fromfifty inches in accordance with ANSI 280.1-1987, 4.6.4 test procedures.

Example 2 Oxygen Barrier Example #1

[0500] A liquid lens forming composition was initially cured as in aprocess and apparatus similar to that specified in Example 1. Thecomposition was substantially the same as specified in Example 1, withthe exception that hydroquinone was absent, the concentration ofmethylethylhydroquinone was about 25-45 ppm, the concentration of1-hydroxycyclohexyl phenyl ketone was 0.017 percent, and theconcentration of methylbenzoylformate was 0.068 percent. The compositionunderwent the initial 15 minute cure under the “1st activating light.”The apparatus was substantially the same as described for the aboveExample 1, with the following exceptions:

[0501] 1. The air flowrate on each side of the lens mold assembly wasestimated to be about 18-20 cubic feet per minute.

[0502] 2. The air flowrate in and out of the chamber surrounding thelights was varied in accordance with the surface temperature of thelights. The air flowrate was varied in an effort to keep the temperatureon the surface of one of the lights between 104.5° F. and 105° F.

[0503] 3. The activating light output was controlled to a set point byvarying the power sent to the lights as the output of the lights varied.

[0504] 4. Frosted glass was placed between the lights and the filtersused to vary the intensity of the activating light across the face ofthe molds. Preferably the glass was frosted on both sides. The frostedglass acts as a diffuser between the lights and these filters. Thisfrosted glass tended to yield better results if it was placed at leastabout 2 mm from the filter, more preferably about 10-15 mm, morepreferably still about 12 mm, from the filter. Frosted glass was foundto dampen the effect of the filters. For instance, the presence of thefrosted glass reduced the systems' ability to produce different lenspowers by varying the light (see Example 1 and FIG. 1).

[0505] After initial cure, the lens mold assembly was removed from thecuring chamber. The lens mold assembly included a lens surrounded by afront mold, a back mold, and a gasket between the front and back molds(see, e.g., the assembly in FIG. 11).

[0506] At this point the protocol in Example I stated that the lens wasdemolded (see above). While demolding at this point is possible, asstated above, generally some liquid lens forming composition remained,especially in areas of the lens proximate the gasket. Therefore, thelens was not demolded as stated in Example 1. Instead, the gasket wasremoved, liquid lens forming composition was wiped off the edges of thelens, and a layer of oxygen barrier (Parafilm M) with photoinitiator waswrapped around the edges of the lens while the lens was still betweenthe molds. The Parafilm M was wrapped tightly around the edges of thelens and then stretched so that it would adhere to the lens and molds(i.e., in a manner similar to that of Saran wrap). The lens moldassembly was then placed in the post-cure unit so that the back face ofthe lens (while between the molds) could then be exposed to additionalactivating light.

[0507] This second activating light was at a substantially higherintensity than the initial cure light, which was directed at anintensity of less than 10 mW/cm². The mold assembly was irradiated withultraviolet light for about 22 seconds. The total light energy appliedduring these 22 seconds was about 4500 millijoules per square centimeter(“mJ/cm²”).

[0508] It has been found that applying activating light at this pointhelped to cure some or all of the remaining liquid lens formingcomposition. The second activating light step may be repeated. In thisexample, the second activating light step was repeated once. It is alsopossible to expose the front or both sides of the lens to the secondactivating light.

[0509] After the second activating light was applied, the mold assemblywas allowed to cool. The reactions caused by exposure to activatinglight may be exothermic. The activating lights also tend to emitinfra-red light which in turn heats the mold assembly. The lens was thendemolded. The demolded lens was substantially drier and harder thanlenses that were directly removed from mold assemblies after the initialcure step.

Example 3 Oxygen Barrier Example #2

[0510] The protocol of Oxygen Barrier Example #1 was repeated exceptthat prior to removal of the gasket the lens mold assembly waspositioned so that the back face of the lens was exposed to thirdactivating light. In this case the third activating light was at thesame intensity and for the same time period as one pass of the secondactivating light. It has been found that applying third activating lightat this point helped to cure some or all of the remaining liquid lensforming composition so that when the gasket was removed less liquid lensforming composition was present. All of the remaining steps in OxygenBarrier Example #1 were applied, and the resultant lens wassubstantially dry when removed from the molds.

Example 4 Conductive Heating Example

[0511] A liquid lens forming composition was initially cured in aprocess and apparatus similar to that specified in Example 1 except forpost-cure treatment, which was conducted as follows:

[0512] After the sample was irradiated for 15 minutes, the lens wasplaced in the post-cure unit to receive a dose of about 1500 mJ/cm²(+/−100 mJ) of activating light per pass. The gasket was then removedfrom the mold assembly and the edges of the mold were wiped with anabsorbent tissue to remove incompletely cured lens forming materialproximate the mold edges. A strip of plastic material impregnated withphotoinitiator was wrapped around the edges of the molds that wereexposed when the gasket was removed. Next, the mold assembly was passedthrough the post-cure unit once to expose the front surface of the moldto a dose of about 1500 mJ/cm². The mold assembly was then passedthrough the post-cure unit four more times, with the back surface of themold receiving a dose of about 1500 mJ/cm² per pass. The heat source ofthe post-cure unit was operated such that the surface of the hot platereached a temperature of 340° F. (+/−50° F.). A conformable “beanbag”container having a covering made of NOMEX fabric was placed on the hotplate. The container contained glass beads and was turned over such thatthe portion of the container that had directly contacted the hot plate(i.e., the hottest portion of the container) faced upward and away fromthe hot plate. The mold assembly was then placed onto the heated,exposed portion of the container that had been in direct contact withthe hot plate. The concave, non-casting face of the mold was placed ontothe exposed surface of the container, which substantially conformed tothe shape of the face. Heat was conducted through the container and themold member to the lens for 13 minutes. A lens having a Shore D hardnessof 84 was formed.

Example 5 Curing Cycles

[0513] Some established cycles are detailed in the table below for threesemi-finished mold gasket sets: a 6.00D base curve, a 4.50D base curve,and a 3.00D base curve. These cycles have been performed with coolingair, at a temperature of about 56° F., directed at the front and backsurfaces of a mold assembly. Frosted diffusing window glass waspositioned between the samples and the lamps, with a layer of PO-4acrylic material approximately 1 inch below the glass. A top lightintensity was adjusted to 760 microwatts/cm² and a bottom lightintensity was adjusted to 950 microwatts/cm², as measured at about theplane of the sample. A Spectroline meter DM365N and standard detectorstage were used. An in-mold coating as described in U.S. Pat. No.5,529,728 to Buazza et. al. was used to coat both the front and backmolds. BASE CURVE Mold Sets 6.00 4.50 3.00 Front Mold 5.95 4.45 2.93Back Mold 6.05 6.80 7.80 Gasket −5.00   13 mm   16 mm ResultingSemifinished Blank Diameter  74 mm   76 mm   76 mm Center Thickness 9.0mm  7.8 mm  7.3 mm Edge Thickness 9.0 mm 11.0 mm 15.0 mm Mass 46 grams48 grams 57 grams Curing Cycle Variables Total Cycle Time 25:00 25:0035:00 Initial Exposure  4:40  4:40  4:35 Number of Pulses 4 4 4 Timing(in seconds) and Duration of Pulses @ Elapsed Time From Onset of InitialExposure Pulse 1 15@10:00 15@10:00 15@13:00 Pulse 2 15@15:00 15@15:0015@21:00 Pulse 3 30@19:00 30@19:00 20@27:00 Pulse 4 30@22:00 30@22:0030@32:00

[0514]FIGS. 26, 27, and 28 each show temperature profiles of theabove-detailed cycles for a case where the activating light exposure iscontinuous and a case where the activating light delivery is pulsed. InFIGS. 26-28, “Io” denotes the initial intensity of the activating lightused in a curing cycle. The phrase “Io=760/950” means that the lightintensity was adjusted to initial settings of 760 microwatts/cm² for thetop lamps and 950 microwatts/cm² for the bottom lamps. The “interiortemperature” of FIGS. 26-28 refers to a temperature of the lens formingmaterial as measured by a thermocouple located within the mold cavity.

Example 6 Pulse Method Using a Medium Pressure Vapor Lamp

[0515] An eyeglass lens was successfully cured with activating lightutilizing a medium pressure mercury vapor lamp as a source of activatinglight (i.e., the UVEXS Model 912 previously described herein). Thecuring chamber included a six inch medium pressure vapor lamp operatingat a power level of approximately 250 watts per inch and a defocuseddichroic reflector that is highly activating light reflective. A highpercentage of infrared radiation was passed through the body of thereflector so that it would not be directed toward the material to becured. The curing chamber further included a conveyer mechanism fortransporting the sample underneath the lamp. With this curing chamber,the transport mechanism was set up so that a carriage would move thesample from the front of the chamber to the rear such that the samplewould move completely through an irradiation zone under the lamp. Thesample would then be transported through the zone again to the front ofthe chamber. In this manner the sample was provided with two distinctexposures per cycle. One pass, as defined hereinafter, consists of twoof these distinct exposures. One pass provided a dosage of approximately275 millijoules measured at the plane of the sample using anInternational Light IL 1400 radiometer equipped with a XRL 340 Bdetector.

[0516] A lens cavity was created using the same molds, lens formingcomposition, and gasket as described in Example 7 below. The reactioncell containing the lens forming material was placed on a supportingstage such that the plane of the edges of the convex mold were at adistance of approximately 75 mm from the plane of the lamp. The lenscavity was then exposed to a series of activating light doses consistingof two passes directed to the back surface of the mold followedimmediately by one pass directed to the front surface of the mold.Subsequent to these first exposures, the reaction cell was allowed tocool for 5 minutes in the absence of any activating radiation at an airtemperature of 74.6 degrees F and at an air flow rate of approximately15 to 25 scf per minute to the back surface and 15 to 25 scf to thefront surface of the cell. The lens cavity was then dosed with one passto the front mold surface and returned to the cooling chamber for 6minutes. Then the back surface was exposed in one pass and then wascooled for 2 minutes. Next, the front surface was exposed in two passesand then cooled for 3.5 minutes. The front surface and the back surfacewere then each exposed to two passes, and the gasket was removed toexpose the edges of the lens. A strip of polyethylene film impregnatedwith photoinitiator was then wrapped around the edge of the lens and thefront and back surfaces were exposed to another 3 passes each. The backsurface of the cell was then placed on the conductive thermal in-moldpostcure device using a “beam-bag” container filled with glass beads ona hot plate at about 340° F. described previously (see Example 4) for atime period of 13 minutes, after which the glass molds were removed fromthe finished lens. The finished lens exhibited a distance focusing powerof −6.09 diopters, had excellent optics, was aberration-free, was 74 mmin diameter, and had a center thickness of 1.6 mm. During the coolingsteps, a small surface probe thermistor was positioned against theoutside of the gasket wall to monitor the reaction. The results aresummarized below. Approx. Elapsed Time After Gasket Wall TemperatureActivating Light Dose Activating Light Dose (min) (° F.) 2 passes toback surface and 1 pass to 0 Not recorded front surface 1 80.5 2 79.7 379.0 4 77.1 5 76.2 1 pass to front surface 0 Not recorded 1 83.4 2 86.53 84.6 4 Not recorded 5 81.4 6 79.5 1 pass to back surface 0 Notrecorded 1 79.3 2 79.0 2 passes to front surface 0 Not recorded 1 78.4 277.8 3 77.0 3.5 76.7

Example 7 Pulse Method Using a Single Xenon Flash Lamp

[0517] An eyeglass lens was successfully cured with activating lightutilizing a xenon flash lamp as a source of activating light. The flashlamp used was an Ultra 1800 White Lightning photographic strobe,commercially available from Paul C. Buff Incorporated of Nashville,Tenn. This lamp was modified by replacing the standard borosilicateflash tubes with quartz flash tubes. A quartz flash tube is preferredbecause some of the activating light generated by the arc inside thetube tends to be absorbed by borosilicate glass. The strobe possessedtwo semicircular flash tubes that trigger simultaneously and the flashtubes were positioned to form a ring approximately 73 millimeters indiameter. The hole in the reflector behind the lamps, which normallycontains a modeling lamp for photographic purposes, was covered with aflat piece of highly-polished activating light reflective material thatis commercially available under the trade name of Alzac from UltraViolet Process Supply of Chicago, Ill. The power selector switch was setto full power. The activating light energy generated from one flash wasmeasured using an International Light IL 1700 Research Radiometeravailable from International Light, Incorporated of Newburyport, Mass.The detector head was an International Light XRL 340 B, which issensitive to radiation in the 326 nm to 401 nm region. The window of thedetector head was positioned approximately 35 mm from the plane of theflash tubes and was approximately centered within the ring formed by thetubes.

[0518] A mold cavity was created by placing two round 80 mm diametercrown glass molds into a silicone rubber ring or gasket that possessed araised lip around its inner circumference. The edges of the glass moldsrested upon the raised lip to form a sealed cavity in the shape of thelens to be created. The inner circumference of the raised lipcorresponded to the edge of the finished lens. The concave surface ofthe first mold corresponded to the front surface of the finished lensand the convex surface of the second mold corresponded to the backsurface of the finished lens. The height of the raised lip of the rubberring into which the two glass molds are inserted controls the spacingbetween the two glass molds, thereby controlling the thickness of thefinished lens. By selecting proper gaskets and first and second moldsthat possess various radii of curvature, lens cavities may be created toproduce lenses of various powers.

[0519] A lens cavity was created by placing a concave glass mold with aradius of curvature of 407.20 mm and a convex glass mold with a radiusof curvature of 65.26 mm into a gasket which provided spacing betweenthe molds of 1.8 mm measured at the center of the cavity. Approximately32 grams of a lens forming monomer was charged into the cavity. The lensforming material used for this test was OMB-91 lens monomer. Thereaction cell containing the lens forming material was placedhorizontally on a supporting stage such that the plane of the edges ofthe convex mold were at a distance of approximately 30 mm from the planeof the flash tubes and the cell was approximately centered under thelight source.

[0520] The back surface of the lens cavity was then exposed to a firstseries of 5 flashes, with an interval of approximately 4 seconds inbetween each flash. The cell was then turned over and the front surfacewas exposed to another 4 flashes with intervals of about 4 seconds inbetween each flash. It is preferable to apply the first set of flashesto the back surface to start to cure the material so that any airbubbles in the liquid monomer will not migrate from the edge of thecavity to the center of the optical zone of the lens. Subsequent tothese first nine flashes, the reaction cell was allowed to cool for fiveminutes in the absence of any activating radiation. To cool the reactioncell, air at a temperature of 71.4 degrees F. and at a flow rate ofapproximately 15 to 25 scf per minute was applied to the back surfaceand air at a temperature of 71.4 degrees F. and at a flow rate ofapproximately 15 to 25 scf per minute was applied to the front surfaceof the cell. The back surface of the lens cavity was then dosed with onemore flash and returned to the cooling chamber for four minutes.

[0521] Next, the cell was exposed to one flash on the front surface andcooled in the cooling chamber for seven minutes. Then the cell wasexposed to one flash on the front surface and one flash on the backsurface and cooled for three minutes. Next, the cell was exposed to twoflashes on the front surface and two flashes on the back surface andcooled for four and a half minutes. The cell was then exposed to fiveflashes each to the back surface and front surface, and the gasket wasremoved to expose the edges of the lens. A strip of polyethylene filmimpregnated with photoinitiator (Irgacure 184) was then wrapped aroundthe edge of the lens, and the cell was exposed to another five flashesto the front surface and fifteen flashes to the back surface. The backsurface of the cell was then placed on the conductive thermal in-moldpostcure device (i.e., “bean bags” filled with glass beads sitting on ahot plate at approx. 340° F.) as described previously (see conductiveheating example above) for a time period of 13 minutes, after which theglass molds were removed from the finished lens. The finished lensexhibited a distance focusing power of −6.16 diopters and a +2.55bifocal add power, had excellent optics, was aberration-free, was 74 mmin diameter, and had a center of thickness of 1.7 mm. During the coolingsteps, a small surface probe thermistor was positioned against theoutside of the gasket wall to monitor the reaction. The results aresummarized below. Dose Elapsed Time From Dose (min) Gasket WallTemperature (F.) 5 flashes to back surface 4 flashes 0 Not recorded tofront surface 1 Not recorded 2 78.4 3 77.9 4 76.9 5 75.9 1 flash to backsurface 0 Not recorded 1 76.8 2 77.8 3 78   4 77.8 1 flash to frontsurface 0 Not recorded 1 79.4 2 81.2 3 81.1 4 79.7 5 78.7 6 77.5 7 77.41 flash to front surface and 1 0 Not recorded flash to back surface 178.8 2 78.8 3 78.0 2 flashes to front surface and 2 0 Not recordedflashes to back surface 1 80.2 2 79.8 3 78.3 4 76.7 4.5 76.3

Example Improved Curing Example

[0522] An 80 mm diameter glass progressive addition mold with a nominaldistance radius of curvature of −6.00 diopters and a +2.50 diopterbifocal add power was sprayed with a mixture of isopropyl alcohol anddistilled water in equal parts and wiped dry with a lint free papertowel. The progressive mold was lenticularized to provide an opticalzone 68 mm in diameter along the 180 degree meridian and 65 mm indiameter along the 90 degree meridian. The non-casting face of the moldwas mounted to a suction cup, which was attached to a spindle. Thespindle was placed on a spin coat unit A one inch diameter pool ofliquid Primer was dispensed into the center of the horizontallypositioned glass mold from a soft polyethylene squeeze bottle equippedwith a nozzle with an orifice diameter of approximately 0.040 inches.The composition of the Primer is discussed in detail below (see ScratchResistant Lens Formation Process Example).

[0523] The spin motor was engaged to rotate the mold at a speed ofapproximately 850 to 900 revolutions per minute, which caused the liquidmaterial to spread out over the face of the mold. Immediatelythereafter, a steady stream of an additional 1.5 to 2.0 grams of Primermaterial was dispensed onto the casting face of the spinning mold withthe nozzle tip positioned at a 45 degree angle approximately 12 mm fromthe mold face such that the stream was flowing with the direction ofrotation of the mold. The stream of Primer material was directed firstat the center of the mold face and then dispensed along the radius ofthe mold face in a direction from the center toward the edge of the moldface. The solvent present in the Primer was allowed to evaporate off for8 to 10 seconds while the mold was rotated. The rotation was stopped andthe Primer coat present on the mold was cured via two exposures to theactivating light output from the medium pressure mercury vapor lamp,totaling approximately 300 mJ/cm².

[0524] The spin motor was again engaged and approximately 1.5 to 2.0grams of HC8-H Hard Coat (see description below), commercially availablefrom the FastCast Corporation of Louisville, Ky. was dispensed onto thespinning mold in a similar fashion as the Primer coat. The solventpresent in the HC8-H was allowed to evaporate off for 25 seconds whilethe mold was rotated. The rotation was stopped and the HC8-H coat wascured in the same manner as the Primer coat.

[0525] The mold was removed from the FlashCure unit and assembled into asilicone rubber gasket in combination with a cleaned convex moldpossessing a radius of curvature of +2.00 diopters. The raised lippresent on the inner circumference of the rubber gasket provided aspacing of 6.3 mm between the two molds at the center point Themold/gasket assembly was positioned on a filling stage and the edge ofthe gasket was peeled back to permit the cavity to be filled with OMB-91lens forming composition, commercially available from the FastCastCorporation of Louisville, Ky. The edge of the gasket was returned toits sealing relationship with the edges of the molds and the excess lensforming composition was vacuumed off the non-casting surface of the backmold with a suction device. The filled mold/gasket assembly was placedon a stage in a lens curing unit and subjected to four exposures of theactivating light output from the six inch medium pressure mercury vaporlamp, totaling approximately 600 mJ/cm².

[0526] Immediately following this initial dose of high intensityactivating light, the assembly was continuously exposed to streams ofair having a temperature of 42° F. while being irradiated with very lowintensity activating light for eight minutes. The light intensitymeasured approximately 90 microwatts/cm² from above plus approximately95 microwatts/cm² from below, according to the plus lens lightdistribution pattern called for by the manufacturer. The lamp racks aretypically configured to deliver activating light having an intensity ofabout 300 microwatt/cm² for the standard fifteen minute curing cycle.The reduction in activating light intensity was accomplished byinserting a translucent high density polyethylene plate into the lightdistribution filter plate slot along with the plus lens lightdistribution plate. A translucent high density polyethylene plate waspositioned between the front mold member and one light distributionplate and between the back mold member and the other light distributionplate.

[0527] The non-casting surface of the back mold was subsequently exposedto four doses of high intensity activating light totaling approximately1150 mJ/cm². The gasket was stripped from the assembly and residualuncured material wiped from the exposed edge of the lens. An oxygenbarrier strip (polyethylene) was wrapped around the edge of the lens andthe mold was exposed to two more doses of high intensity activatinglight totaling 575 mJ/cm² to the non-casting surface of the front moldfollowed by eight more flashes to the non-casting surface of the backmold totaling 2300 mJ/cm².

[0528] The non-casting surface of the back mold was placed in contactwith a thermal transfer pad, commercially available from the FastCastCorporation of Louisville, Ky., at a temperature of approximately 150 to200° F. for thirteen minutes. The assembly was removed from the thermaltransfer pad and the back mold was removed with a slight impact from anappropriately sized wedge. The front mold with the lens attached theretowas placed in a container of room temperature water and the lensseparated from the front mold. The now-finished lens was sprayed with amixture of isopropyl alcohol and water in equal parts and wiped dry. Thelens read +3.98 D with an addition power of +2.50, was clear,non-yellow, and exhibited good optics.

Example 9 Scratch Resistant Lens Formation Example

[0529] A first coating composition, hereinafter referred to as “Primer”,was prepared by mixing the following components by weight:

[0530] 93.87% acetone;

[0531] 3.43% SR-399 (dipentaerythritol pentaacrylate), available fromSartomer;

[0532] 2.14% CN-104 (epoxy acrylate), available from Sartomer;

[0533] 0.28% Irgacure 184 (1-hydroxycyclohexylphenylketone), availablefrom Ciba-Geigy; and

[0534] 0.28% Darocur 1173 (2-hydroxy-2-methyl-1-phenyl-propan-1-one)available from Ciba-Geigy.

[0535] A second coating composition, hereinafter referred to as “HC8-H”was prepared by mixing the following components by weight:

[0536] 84.69% 1-methoxy 2-propanol;

[0537] 9.45% SR-399 (dipentaerythritol pentaacrylate), available fromSartomer;

[0538] 4.32% SR601 (ethoxylated bisphenol A diacrylate), available fromSartomer, and

[0539] 1.54% Irgacure 184 (1-hydroxycyclohexyl phenyl ketone), availablefrom Ciba-Geigy.

[0540] Each of these coating compositions was prepared by firstdissolving the monomers into the solvent, then adding thephotoinitiators, mixing well, and finally passing the compositionthrough a one micron filter prior to use.

[0541] An 80 mm diameter glass, 28 mm flattop mold with a distanceradius of curvature of −6.00 diopters and a +2.00 diopter bifocal addpower were sprayed with a mixture of isopropyl alcohol and distilledwater in equal parts. The flattop mold was wiped dry with a lint freepaper towel. The non-casting face of the mold was mounted to a suctioncup, which was attached to a spindle. The spindle was placed on the spincoating unit.

[0542] A one inch diameter pool of liquid Primer was dispensed into thecenter of the horizontally positioned glass mold. The Primer wasdispensed from a soft polyethylene squeeze bottle equipped with a nozzlehaving an orifice diameter of approximately 0.040 inches. A spin motorof the spinning device was engaged to rotate the mold at a speed ofapproximately 850 to 900 revolutions per minute, causing the liquidPrimer to spread out over the face of the mold. Immediately thereafter,a steady stream of an additional 1.5 to 2.0 grams of Primer material wasdispensed onto the casting face of the spinning mold. The stream ofPrimer material was directed onto the casting face with the nozzle tippositioned at a 45 degree angle approximately 12 mm from the mold face.This positioning of the nozzle tip made the stream to flow with thedirection of rotation of the mold. The stream of Primer material wasdirected first at the center of the mold face and then dispensed alongthe radius of the mold face in a direction from the center toward theedge of the mold face.

[0543] The solvent present in the Primer was allowed to evaporate offfor 8 to 10 seconds during rotation of the mold. The rotation wasstopped and the Primer coat which remained on the mold was cured via twoexposures to the activating output from a medium pressure mercury vaporlamp, totaling approximately 300 mJ/cm². All light intensity/dosagemeasurements cited herein were taken with an International Light IL-1400Radiometer equipped with an XLR-340B Detector Head, both commerciallyavailable from International Light, Inc. of Newburyport, Mass.

[0544] Upon exposure to the activating light, the spin motor was againengaged and approximately 1.5 to 2.0 grams of HC8-H Hard Coat,commercially available from the FastCast Corporation of Louisville, Ky.was dispensed onto the spinning mold in a similar fashion as the Primercoat. The solvent present in the HC8-H was allowed to evaporate off for25 seconds while the mold was spinning. The rotation was stopped, andthe HC8-H coat was cured in the same manner as the Primer coat.

[0545] The mold was removed from the spin coating unit and assembledinto a silicone rubber gasket in combination with a cleaned convex moldpossessing a radius of curvature of +7.50 diopters. The raised lippresent on the inner circumference of the rubber gasket provided aspacing of 1.8 mm between the two molds at the center point. At thispoint, the mold/gasket assembly was positioned on a filling stage andthe edge of the gasket was peeled back to permit the cavity to be filledwith OMB-91 lens forming composition, commercially available from theFastCast Corporation of Louisville, Ky. The edge of the gasket wasreturned to its sealing relationship with the edges of the molds and theexcess lens forming composition was vacuumed off the non-casting surfaceof the back mold with a suction device.

[0546] The filled mold/gasket assembly was transferred from the fillingstage to a lens curing unit. While in the lens curing unit, the assemblywas continuously irradiated with activating light from both sides for aperiod of 15 minutes at approximately 300 microwatts/cm² from above andat approximately 350 microwatts/cm² from below, according to the minuslens light distribution pattern called for by the manufacturer. Duringthe irradiation, the casting cell was continuously exposed to streams ofair having a temperature of 42° F.

[0547] The non-casting surface of the back mold was exposed to fourdoses of high intensity activating light totaling approximately 1150mJ/cm². The gasket was stripped from the assembly and residual uncuredmaterial was wiped from the exposed edge of the lens. An oxygen barrierstrip (polyethylene) was wrapped around the edge of the lens. Themold/gasket assembly was exposed to two more doses of high intensityactivating light, wherein 575 mJ/cm² total was directed to thenon-casting surface of the front mold. Subsequently, eight more flashesof the activating light were directed to the non-casting surface of theback mold, totaling 2300 mJ/cm².

[0548] The non-casting surface of the back mold was placed in contactwith a thermal transfer pad, commercially available from the FastCastCorporation of Louisville, Ky, at a temperature of approximately 150 to200° F. for thirteen minutes. The mold/gasket assembly was removed fromthe thermal transfer pad, and the back mold was removed with a slightimpact from an appropriately sized wedge. The front mold with the lensattached thereto was placed in a container of room temperature water.While within the water, the lens became separated from the front mold.The now-finished lens was sprayed with a mixture of isopropyl alcoholand water in equal parts and wiped dry.

[0549] The lens was positioned in a holder and placed into a heated dyepot for 5 minutes. The dye pot contained a solution of BPI Black,commercially available from Brain Power, Inc. of Miami, Fla., anddistilled water at a temperature of approximately 190 degrees F. Thelens was removed from the dye pot, rinsed with tap water, and wiped dry.The lens exhibited a total visible light absorbance of approximately80%. When inspected for cosmetic defects on a light table, no pinholedefects were observed. Further, the tint which had been absorbed by theback surface of the lens was found to be smooth and even.

Example 10 Formation of a Plastic Lens Containing Photochromic Material

[0550] A polymerizable mixture of PRO-629 (see above for a descriptionof the components of PRO-629), photochromic pigments, and aphotoinitiator/co-initiator system was prepared according to thefollowing procedure. A photochromic stock solution was prepared bydissolving the following pigments into 484 grams of HDDMA Pigment grams% by wt. Dye #94 1.25 0.250% Dye #266 0.45 0.090% Variacrol Red PNO 2.660.532% Variacrol Yellow L 1.64 0.328% Reversacol Corn Yellow 3.58 0.716%Reversacol Berry Red 2.96 0.590% Reversacol Sea Green 2.17 0.434%Reversacol Palatinate Purple 1.29 0.258% Total 16.0 3.200%

[0551] Dye #94 and Dye #266 are indilino-spiropyrans commerciallyavailable from Chroma Chemicals, Inc. in Dayton, Ohio. Variacrol Red PNOis a spiro-napthoxazine material and Variacrol Yellow L is a napthopyranmaterial, both commercially available from Great Lakes Chemical in WestLafayette, Ind. Reversacol Corn Yellow and Reversacol Berry Red arenapthopyrans and Reversacol Sea Green, and Reversacol Palatinate Purpleare spiro-napthoxazine materials commercially available from KeystoneAnaline Corporation in Chicago, Ill.

[0552] The powdered pigments were weighed and placed in a beaker. TheHDDMA was added to the powdered pigments, and the entire mixture washeated to a temperature in the range from about 50° C. to 60° C. andstirred for two hours. Subsequently, the photochromic stock solution wascooled to room temperature and then gravity fed through a four inch deepbed of aluminum oxide basic in a one inch diameter column. Prior topassing the stock solution through the alumina, the alumina was washedwith acetone and dried with air. The remaining HDDMA was forced out ofthe alumina with pressurized air. It is believed that this filtrationstep removes any degradation by-products of the photochromic pigmentsand/or any impurities present in the mixture. After the filtration step,the stock solution was passed through a 1 micron filter to remove anyalumina particles which may have passed out of the column with the stocksolution.

[0553] A photoinitiator stock solution containing a photoinitiatorcombined with an ultraviolet/visible light absorber was also prepared bymixing 2.56 grams of CGI-819 and 0.2 grams of Tinuvin 400, anultraviolet/visible light absorber commercially available from CibaAdditives of Tarrytown, N.Y., with 97.24 grams of PRO-629. The stocksolution was stirred for two hours at room temperature in the absence oflight. The photoinitiator stock solution was then filtered by passing itthrough a layer of alumina and a one micron filter. The stock solutionwas placed in an opaque polyethylene container for storage.

[0554] A background dye stock solution was prepared by mixing 50 gramsof a 422 ppm solution of A241/HDDMA, 50 grams of a 592 ppm solution ofThermoplast Red 454/HDDMA, 50 grams of 490 ppm solution of Zapon Brown286/HDDMA, 50 grams of 450 ppm solution of Zapon Brown 287/HDDMA, 50grams of 1110 ppm solution of Oil Soluble Blue II/HDDMA, and 50 grams ofa 1110 ppm solution of Thermoplast Blue P/HDDMA, all with 700 grams ofPRO-629. The entire mixture was heated to a temperature ranging fromabout 50° C. to 60° C. and subsequently stirred for two hours.

[0555] A lens forming composition was prepared by adding 12.48 grams ofthe above described photochromic stock solution, 10 grams of thephotoinitiator stock solution, 27 grams of the background dye stocksolution, and 7.3 grams of the NMDEA co-initiator to 943.22 grams ofPRO-629. The components of the lens forming composition were stirred atroom temperature for several minutes until well mixed. This compositionis hereafter referred to as PC #1. The PC#1 contained the followingamounts of components. Component Amount Tripropyleneglycol diacrylate31.16% Tetraethyleneglycol diacrylate 20.45% Trimethylolpropanetriacrylate 19.47% Bisphenol A bis allyl carbonate 16.55% Hexanedioldimethacrylate 11.56% Dye #94 31.20 ppm Dye #266 11.20 ppm Variacrol RedPNO 66.40 ppm Variacrol Yellow L 40.90 ppm Reversacol Corn Yellow 89.30ppm Reversacol Berry Red 73.60 ppm Reversacol Sea Green 54.20 ppmReversacol Palatinate Purple 32.20 ppm A241 0.57 ppm Thermoplast Red 4540.80 ppm Zapon Brown 286 0.66 ppm Zapon Brown 287 0.61 ppm Oil SolubleBlue II 1.50 ppm Thermoplast Blue 1.50 ppm CGI-819 255.90 ppm NMDEA0.73% Tinuvin 400 20.00 ppm

[0556] An 80 mm diameter concave glass progressive addition mold havinga distance radius of curvature of 6.00 diopters and a +1.75 diopterbifocal add power was sprayed with a mixture of isopropyl alcohol anddistilled water in equal parts and wiped dry with a lint free papertowel. The mold was then mounted with its casting face upward on thecenter of a stage. The mold was fixed securely to the stage using threeequidistant clip-style contact points to hold the periphery of the mold.The mold stage had a spindle attached to it which was adapted to connectto a spin coating device. The mold stage, with the mold affixed, wasplaced within the spin coating device. The mold was rotated atapproximately 750 to 900 revolutions per minute. A stream of isopropylalcohol was directed at the casting surface while the casting surfacewas simultaneously brushed with a soft camel hair brush to clean thesurface. After the cleaning step, the mold surface was dried bydirecting a stream of reagent grade acetone over the surface andallowing it to evaporate off, all while continuing the rotation of themold.

[0557] The rotation of the mold was then terminated and a one inchdiameter pool of a liquid coating composition was dispensed into thecenter of the horizontally positioned glass mold from a softpolyethylene squeeze bottle equipped with a nozzle having an orificediameter of approximately 0.040 inches. The spin motor was engaged torotate the mold at a speed of approximately 750 to 900 revolutions perminute, causing the liquid material to spread out over the face of themold. Immediately thereafter, a steady stream of an additional 1.5 to2.0 grams of the coating composition was dispensed onto the casting faceof the spinning mold. The stream was moved from the center to the edgeof the casting face with a nozzle tip positioned at a 45° angleapproximately 12 mm from the mold face. Thus, the stream was flowingwith the direction of rotation of the mold.

[0558] The solvent present in the coating composition was allowed toevaporate while rotating the mold for 10 to 15 seconds. The rotation wasstopped, and then the coating composition on the mold was cured via atotal exposure of approximately 300 mJ/cm² of activating light The lightwas provided from a medium pressure mercury vapor lamp. All lightintensity/dosage measurements cited herein were taken with anInternational Light IL-1400 Radiometer equipped with an XLR-340BDetector Head, both commercially available from International Light,Inc. of Newburyport, Mass. At this point, the spin motor was againengaged and approximately 1.5 to 2.0 grams of additional coatingcomposition was dispensed onto the spinning mold. The solvent of thecomposition was allowed to evaporate, and the composition was cured in asimilar fashion to the first layer of coating composition.

[0559] The above described coating composition comprised the followingmaterials: Material % by wt. Irgacure 184 0.91% Tinuvin 770 0.80% CN-1042.00% SR-601 1.00% SR-399 8.60% Acetone 26.00% Ethanol 7.00%1-Methoxypropanol 53.69%

[0560] Irgacure 184 is a photoinitiator commercially available from CibaAdditives, Inc. CN-104 is an epoxy acrylate oligomer, SR-601 is anethoxylated bisphenol A diacrylate, and SR-399 is dipentaerythritolpentaacrylate, all available from Sartomer Company in Exton, Pa. Theacetone, the ethanol, and the 1-methoxypropanol were all reagent gradesolvents. The Tinuvin 770 improves the impact resistance of the lens andis available from Ciba Additives, Inc.

[0561] An 80 mm diameter convex mold with radii of curvature of6.80/7.80 diopters was cleaned and coated using the same proceduredescribed above except that no pooling of the coating compositionoccurred in the center of the mold when the composition was dispensedthereto.

[0562] The concave and convex molds were then assembled together with asilicone rubber gasket. A raised lip on the inner circumference of therubber gasket provided a spacing of 2.8 mm between the two molds at thecenter point. At this point the mold/gasket assembly was positioned on afilling stage. The edge of the gasket was peeled back to permit thecavity to be filled with PC #1 lens forming composition. The edge of thegasket was returned to its sealing relationship with the edges of themolds, and the excess lens forming composition was vacuumed from thenon-casting surface of the back mold with a suction device. The filledmold/gasket assembly was then transferred from the filling stage to alens curing unit. The assembly was placed with the back mold facingupward on a black stage configured to hold the mold/gasket assembly.

[0563] An activating light filter was then placed on top of the backmold. The filter was approximately 80 mm in diameter which is the sameas the mold diameter. The filter also had a spherical configuration witha center thickness of 6.7 mm and an edge thickness of 5.5 mm. The filterwas taken from a group of previously made filters. These filters wereformed by using eyeglass lens casting molds and gaskets to createcavities that were thickest in the center (a plus spherical cavity) andcavities that were thinnest in the center (a minus spherical cavity). Atoric component was also incorporated with some of these cavities toform compound cavities.

[0564] The filter cavities were filled with an activating light curablecomposition comprising by weight: 99.37% PRO629, 0.35% K-Resin, 0.27%NMDEA, 121 ppm CGI-819, and 10 ppm Tinuvin 400. K-resin is astyrene-butadiene copolymer commercially available from PhillipsChemical Company. To form this composition, the K-resin was firstdissolved in toluene. An appropriate amount of the K-resin toluenesolution was added to the PRO-629, and then the toluene was evaporatedoff by heat and stirring. The NMDEA, CGI-19, and the Tinuvin 400 werethen added to the PRO-629/K-Resin solution. The compositions containedin the cavities were cured by exposure to activating light When thecured article was removed from the mold cavity, it exhibited a highdegree of haze caused by the incompatibility of the PRO-629. and theK-Resin. In the strictest sense of the word, it should be noted thatthese filters were not “lenses” because their function was not to focuslight but rather to scatter and diffuse light.

[0565] The mold/gasket assembly and the filter were then irradiated withfour consecutive doses of activating light totaling approximately 1150mJ/cm², as previously measured at the plane of the mold cavity with nofilter or any other intervening media between the light source and theplane. The mold/gasket assembly was then turned over on the stage sothat the front mold was facing upward. The mold/gasket assembly wasfurther rotated 90 degrees around the paraxial axis from its originalposition. The light filter was then placed over the front mold. Theentire assembly was then exposed to two more doses of activating lighttotaling approximately 575 mJ/cm². The mold/gasket assembly was removedfrom the curing chamber. The gasket was removed from the molds, and theexposed edge of the lens was wiped to remove any residual liquid. Themolds with lens were then placed in a vertical orientation in a rack,and the non-casting faces of both the front and back molds were exposedto ambient room temperature air for a period of approximately tenminutes. Then, without the aforementioned light filter in place, themold assembly was dosed with four exposures totaling 600 mJ/cm² directedtoward the back mold and two exposures totaling 300 mJ/cm² directedtoward the front mold.

[0566] Subsequent to these exposures, the junction of the back mold andthe lens was scored with the edge of a brass spatula. The back mold wasthen removed from the lens by positioning an appropriate sized Delrinwedge between the front and back molds and applying a sharp impact tothe wedge. The lens, along with the front mold to which it was attached,was held under running tap water and simultaneously brushed with a softbrush to remove any flakes or particles of polymer from the edges andsurface of the lens. The front mold was then separated from the lens bybreaking the seal between the two with the point of a pin pressedagainst the junction of the front mold and the lens. The lens was thenplaced concave side upward on a lens stage of similar design to the moldstage, except that the peripheral clips were configured to secure asmaller diameter workpiece. The lens stage, with the lens affixed, waspositioned on the spin coating unit and rotated at about 750 to 900revolutions per minute. A stream of isopropyl alcohol was directed atthe concave surface while simultaneously brushing the surface with asoft, clean brush.

[0567] After brushing, a stream of isopropyl alcohol was directed at thesurface of the lens, and the rotation was continued for a period ofapproximately 30 seconds until the lens was dry. The lens was turnedover on the stage so that the convex surface of the lens faced upward.Then the cleaning procedure was repeated on the convex surface. With theconvex surface facing upward, the lens was dosed with four exposures ofactivating light totaling approximately 1150 mJ/cm². The lens was againturned over on the stage such that the concave surface was upward. Thelens was subjected to an additional two exposures totaling 300 mJ/cm².The lens was removed from the stage and placed in a convection oven at115° C. for five minutes. After annealing the lens, it was removed fromthe oven and allowed to cool to room temperature. At this point the lenswas ready for shaping by conventional means to fit into an eyeglassframe.

[0568] The resulting lens was approximately 72 mm in diameter. The lenshad a center thickness of 2.6 mm, a distance focusing power of−0.71-1.00 diopters, and a bifocal addition strength of 1.74 diopters.The lens appeared to have a bleached color of tan Also, the lens thatwas formed exhibited approximately 75% visible transmittance as measuredwith a Hoya ULT-3000 meter. The lens was exposed to midday sunlight at atemperature of approximately 75° F. for 3 minutes. After being exposedto sunlight, the lens exhibited a gray color and a visible lighttransmittance of approximately 15%. The optics of the lens appeared tobe crisp, without aberrations in either the distance or the bifocalsegment regions. The same lens forming composition was cured to form aplano lens so that the lens could be scanned with a Hewlett PackardModel 8453 UV-Vis spectrophotometer. See FIG. 30 for a plot of %transmittance versus wavelength (nm), as exhibited by the plano lens inits lightened state (i.e., without sunlight exposure). The lensexhibited very little transmittance of light at wavelengths below about370 nm.

[0569] The eyeglass lens of this example was formed from a lens formingcomposition included ultraviolet/visible light absorbing photochromiccompounds by using activating light. Since photochromic pigments tend toabsorb ultraviolet/visible light strongly, the activating light mightnot have penetrated to the depths of the lens forming composition. Thelens forming composition, however, contained a co-initiator inconjunction with a photoinitiator to help promote the curing of theentire lens forming composition. The present example thus demonstratesthat a photochromic lens containing both a photoinitiator and aco-initiator may be cured using activating light to initiatepolymerization of the lens forming composition.

Example 11 Casting a Colorless Lens Containing Ultraviolet/Visible LightAbsorbers

[0570] According to a preferred embodiment, a polymerizable mixture ofPRO-629 (see above for a description of the components of PRO-629),colorless ultraviolet/visible light absorbing compounds, an ultravioletstabilizer, background dyes, and a photoinitiator/co-initiator packagewas prepared according to the following procedure. Six separate stocksolutions were prepared. One stock solution contained thephotoinitiator, two stock solutions contained ultraviolet/visible lightabsorbing compounds, one stock solution contained co-initiators, onestock solution contained an ultraviolet light stabilizer, and one stocksolution contained a background dye package. Each of these stocksolutions were treated by passing them through a one inch diametercolumn packed with approximately 30 grams of alumina basic. It isbelieved that this step reduced the impurities and trapped the acidicbyproducts present in each of the additives to the PRO-629. Thefollowing is a detailed description of the preparation of thepolymerizable mixture mentioned above.

[0571] About 500 grams of a photoinitiator stock solution was preparedby dissolving 2.5% by weight of bis(2,6-dimethoxybenzoyl)(2,4,4-trimethyl-phenyl) phosphine oxide (CGI-819 commercially availablefrom Ciba Additives) in Pro-629. This mixture was passed through analumina basic column in the dark.

[0572] About 500 grams of the ultraviolet light absorber stock solutionwas prepared by dissolving 2.5% by weight of2(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethyl)phenol (98% purity) inPRO-629. This mixture was also passed through an alumina basic column.

[0573] About 500 grams of a co-initiator stock solution was prepared bymixing 70% by weight of CN-384 (a reactive amine co-initiatorcommercially available from Sartomer Company) in Pro-629. This mixturewas passed through an alumina basic column.

[0574] About 271 grams of an ultraviolet light stabilizer stock solutionwas prepared by mixing 5.55% by weight of Tinuvin 292 in PRO-629. Thismixture was passed through an alumina basic column.

[0575] About 250 grams of an ultraviolet/visible light absorber stocksolution was prepared by mixing 5.0% Tinuvin 400 (a mixture of2-[4-((2-hydroxy-3-dodecyloxypropyl)oxy)2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazineand2-[4-(2-hydroxy-3-tridecyloxypropyl)-oxy)-2-hydroxyphenyl]4,6bis(2,4-dimethylphenyl)-1,3,5-triazine)by weight in PRO-629. This mixture was passed through an alumina basiccolumn.

[0576] About 1000 grams of a background dye stock solution was preparedby mixing about 50 grams of a 592 ppm solution of Thermoplast Red454/HDDMA, 50 grams of 490 ppm solution of Zapon Brown 286/HDDMA, 50grams of 450 ppm solution of Zapon Brown 287/HDDMA, 50 grams of 1110 ppmsolution of Oil Soluble Blue II(HDDMA, and 50 grams of a 1110 ppmsolution of Thermoplast Blue P/HDDMA, all with 750 grams of PRO-629. Theentire mixture was heated to a temperature between about 50° and 60° C.and stirred for two hours. This mixture was passed through an aluminabasic column.

[0577] About 250 grams of CN-386 (a reactive amine co-initiatorcommercially available from Sartomer Company) was passed through analumina basic column.

[0578] A lens forming composition was prepared by mixing 967.75 grams ofPRO-629 with 12.84 grams of the 2.5%2(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethyl)phenolultraviolet/visible light absorber stock solution, 4.3 grams of the 70%CN-384 co-initiator stock solution, 8.16 grams of the 2.5% CGI-819photoinitiator stock solution, 0.53 grams of the CN-386, 1.54 grams ofthe Tinuvin 400 ultraviolet/visible light absorber stock solution, 0.92grams of the Tinuvin 292 ultraviolet light stabilizer stock solution,and 4.0 grams of the background dye stock solution. The resulting lensforming composition contained the following components: Material % byweight PRO-629 99.10%2(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethyl)phenol   321 ppm Tinuvin400   77 ppm Tinuvin 292   51 ppm CN-384  0.3% CN-386  0.53% CGI-819  204 ppm Thermoplast Red  0.12 ppm Zapon Brown 286  0.10 ppm ZaponBrown 287  0.10 ppm Oil Soluble Blue II  0.22 ppm Thermoplast Blue  0.22ppm

[0579] An 80 mm diameter flattop concave glass mold with a distanceradius of curvature of 2.85 diopters and a +3.00 diopter bifocal addpower was cleaned and coated as described in Example 10.

[0580] An 80 mm diameter convex mold with radii of curvature of 7.05diopters was cleaned and coated in the same fashion described aboveexcept that no pooling of the coating composition occurred in the centerof the mold when the composition was dispensed thereto.

[0581] Both the concave and convex molds were then provided with a curedadhesion-promoting coating composition. By providing such a coating, theadhesion between the casting surface of the glass mold and the lensforming composition was increased, thereby reducing the possibility ofpremature release of the lens from the mold. The coating furtherprovided abrasion resistance, chemical resistance, and improvedcosmetics to the finished lens.

[0582] The concave and convex molds were then assembled and placedwithin a lens curing unit as described in Example 10.

[0583] An activating light filter was then placed on top of the backmold. The filter was approximately 80 mm in diameter which is the sameas the mold diameter. It had a plano configuration with a thickness of3.1 mm. This filter transmitted approximately 30% of the incidentactivating light from the source as measured using the IL 1400radiometer with a XRL-340B detector head. The filter was taken from agroup of previously made filters. The fabrication of these filters wasdiscussed in Example 10.

[0584] The mold/gasket assembly in which the lens forming compositionhad been placed and which had been covered by the above described filterwas then irradiated with four consecutive doses of activating lighttotaling approximately 600 mJ/cm², as measured using the IL-1400Radiometer equipped with the XLR-340B detector. This measurement wastaken at the plane of the mold cavity while no filter or any interveningmedia was present between the light source and the plane. Themold/gasket assembly was then turned over on the stage so that the frontmold was facing upward. The mold/gasket assembly was further rotated 90degrees around the paraxial axis from its original position. The lightfilter was then replaced over the front mold. The entire assembly wasexposed to two more doses of activating light totaling approximately 300mJ/cm².

[0585] The mold/gasket assembly was then removed from the curingchamber, and the gasket was removed from the assembly. The mold was thenreturned to the lens curing chamber such that the back mold was facingupward. An opaque rubber disc, approximately 80 mm in diameter wasplaced over the back mold. This disc had the function of preventingactivating light from impinging on the major portion of the materialcontained within the cavity. With the disc in position, the cell wasexposed to two more exposures at 300 mn/ cm². This subsequent exposurewas used to cure the residual liquid around the edges of the lens,particularly around the junction between the front mold and the lens andto help seal the periphery. The mold assembly was removed from thecuring chamber and placed in a vertical orientation in a rack. Thenon-casting faces of both the front and back molds were then exposed toambient room temperature air for a period of approximately fifteenminutes. At this point, the entire mold assembly was dosed with twoexposures totaling 300 mJ/cm² directed toward the back mold and twoexposures totaling 300 mJ/cm² directed toward the front mold, withoutthe aforementioned light filter or opaque disc in place.

[0586] The lens was removed from the mold assembly and post-cured asdescribed in Example 10.

[0587] The resulting lens was approximately 72 mm in diameter, had acenter thickness of 1.5 mm, a distance focusing power of −4.08 diopters,and a bifocal addition strength of 3.00 diopters. The resultant lens waswater white. The optics of the lens were crisp, without aberrations ineither the distance or the bifocal segment regions. The same lensforming composition was cured to form a plano lens. The plano lens wasscanned with a Hewlett Packard Model 8453 UV-Vis spectrophotometer. SeeFIG. 31 for a plot of % transmittance versus wavelength (nm), asexhibited by the photochromic lens when exposed to sunlight. The lensexhibited virtually no transmittance of light at wavelengths below about370 nm. Also shown in FIG. 31 are the results of a similar scan made ona plano lens formed using the OMB-91 lens forming composition (seeCuring by the Application of Pulsed Activating Light above forcomponents of OMB-91). The OMB-91 lens, which has no ultraviolet/visiblelight absorbing compounds, appears to transmit light at wavelengthsshorter than 370 nm, unlike the colorless lens that containedultraviolet/visible light absorbing compounds.

[0588] The eyeglass lens of this example was cured using activatinglight even though the lens forming composition included activating lightabsorbing compounds. Since activating light absorbing compounds tend toabsorb activating light strongly, the activating light might not havepenetrated to the depths of the lens forming composition. The lensforming composition, however, contained a co-initiator in conjunctionwith a photoinitiator to help promote the curing of the entire lensforming composition. The present example thus demonstrates that a lenscontaining ultraviolet/visible light absorbing compounds may be curedusing activating light to initiate polymerization of a lens formingcomposition which contains a photoinitiator/co-initiator system. Thelens was also produced using activating light of comparable intensityand duration as was used for the production of photochromic lenses.Thus, the addition of ultraviolet/visible light absorbers to anon-photochromic lens forming composition, allows both photochromic andnon-photochromic lens forming compositions to be cured using the sameapparatus and similar procedures.

Example 12 Casting a Colored Lens Containing Ultraviolet/Visible LightAbsorbers

[0589] According to a preferred embodiment a polymerizable mixture ofPRO-629 (see above for a description of the components of PRO-629),fixed pigments, and a photoinitiator/co-initiator package was preparedaccording to the following procedure. Nine separate stock solutions wereprepared. Seven of the stock solutions contained fixed pigments, one ofthe stock solutions contained an ultraviolet/visible light absorbingcompound, and one of the stock solutions contained a photoinitiator.Each of these stock solutions were treated by passing them through a oneinch diameter column packed with approximately 30 grams of aluminabasic. It is believed that this step reduces the impurities and trapsthe acidic byproducts present in each of the additives to the PRO-629.

[0590] For each of the following fixed pigments, a stock solution wasprepared by the following procedure. The pigments used were ThermoplastRed 454, Thermoplast Blue P, Oil Soluble Blue II, Zapon Green 936, ZaponBrown 286, Zapon Brown 287, and Thermoplast Yellow 284. One gram of eachpigment was dissolved in 499 grams of HDDMA. Each mixture was heated toa temperature in the range of from about 50° C. to about 60° C. forapproximately two hours. This mixture was passed through an aluminabasic column. The alumina was then washed with 200 grams of HDDMA at atemperature of about 50° C. to about 60° C. followed by 300 grams ofPRO-629 at a temperature of about 50° C. to about 60° C. This washingstep ensured that any pigments trapped in the alumina were washed intothe stock solution. This resulted in stock solutions which contained a0.1% concentration of each pigment in 29.97% PRO-629 and 69.93% HDDMA.

[0591] About 250 grams of the ultraviolet/visible light absorber stocksolution was prepared by dissolving 5.0% Tinuvin 400 by weight inPRO-629. This mixture was passed through an alumina basic column.

[0592] About 500 grams of the photoinitiator stock solution was preparedby dissolving 2.5% by weight of bis(2,6-dimethoxybenzoyl)(2,4,4-trimethylphenyl)phosphine oxide (CGI-819 commercially availablefrom Ciba Additives) in PRO-629. This mixture was passed through analumina basic column in the dark.

[0593] A lens forming composition was prepared by mixing 685.3 grams ofPRO-629 with 10.48 grams of the 2.5% CGI-819 photoinitiator stocksolution, 5.3 grams of NMDEA (N-methyldiethanolamine is commerciallyavailable from Aldrich Chemicals), 0.6 grams of Tinuvin 400ultraviolet/visible light absorber stock solution, 7 grams of theThermoplast Red stock solution, 58.3 grams of the Thermoplast Blue stocksolution, 55.5 of the Oil Soluble Blue II stock solution, 29.2 grams ofthe Zapon Green 936 stock solution, 68.1 grams of the Zapon Brown 286stock solution, 38.9 grams of the Zapon Brown 287 stock solution, and41.3 grams of the Thermoplast Yellow 104 stock solution. The resultinglens forming composition contained the following components: Material %by weight Bisphenol A bis allyl carbonate 13.35% Tripropyleneglycoldiacrylate 25.13% Tetraethyleneglycol diacrylate 16.49%Trimethylolpropane triacrylate 15.71% Hexanediol dimethacrylate 28.75%Thermoplast Red  7.0 ppm Zapon Brown 286  68.1 ppm Zapon Brown 287  38.9ppm Oil Soluble Blue II  55.5 ppm Thermoplast Blue  58.3 ppm Zapon Green936  29.2 ppm Thermoplast Yellow 104  41.3 ppm NMDEA  0.53% CGI-819  262 ppm Tinuvin 400   30 ppm

[0594] An 80 mm diameter flattop concave glass mold with a distanceradius of curvature of 6.0 diopters was cleaned and coated as describedin Example 10.

[0595] An 80 mm diameter convex mold with radii of curvature of 6.05diopters was cleaned and coated in the same fashion except that nopooling of the coating composition occurred in the center of the moldwhen the composition was dispensed thereto.

[0596] The concave and convex molds were then coated with a curedadhesion-promoting coating composition. By providing such a coating, theadhesion between the casting surface of the glass mold and the curinglens forming composition was increased, thereby reducing the possibilityof premature release of the lens from the mold. The coating alsoprovided abrasion resistance, chemical resistance, and improvedcosmetics to the finished lens.

[0597] The concave and convex molds were then assembled and placedwithin a lens curing unit as described in Example 10.

[0598] An activating light filter was then placed on top of the backmold. The filter was approximately 80 mm in diameter, which is the sameas the mold diameter. It had a plano configuration with a thickness of3.1 mm. This filter transmitted approximately 30% of the incidentactivating light from the source as measured using the IL 1400radiometer with a XRL-340B detector head. The filter was taken from agroup of previously made filters. The fabrication of these filters wasdiscussed in Example 10.

[0599] The mold/gasket assembly containing the lens forming compositionwas then irradiated with six consecutive doses of activating lighttotaling approximately 1725 mJ/cm², as previously measured using theIL-1400 Radiometer equipped with the XLR-340B detector, at the plane ofthe mold cavity with no filter or any intervening media between thelight source and the plane. The mold/gasket assembly was then turnedover on the stage so that the front mold was facing upward. The entireassembly was then exposed to six more doses of activating light totalingapproximately 1725 mJ/cm². The mold/gasket assembly was removed from thecuring chamber. The gasket was removed from the molds, and the assemblywas placed in a vertical orientation in a rack such that the noncastingfaces of both the front and back molds were exposed to ambient roomtemperature air for a period of approximately ten minutes. At thispoint, the assembly was returned to the lens curing chamber and wasdosed with four exposures totaling 600 mJ/cm² directed toward the backmold and four exposures totaling 600 mJ/cm² directed toward the frontmold.

[0600] The lens was removed from the mold assembly and post-cured asdescribed in Experiment 10.

[0601] The resulting lens was approximately 74 mm in diameter, had acenter thickness of 2.7 mm, and a distance focusing power of +0.06diopters. The resultant lens was dark green/grayish in color and couldbe used as a sunglass lens. The optics of the lens were crisp, withoutaberrations. The lens exhibited visible light transmission ofapproximately 10%. When scanned with a Hewlett Packard Model UV-Visspectrophotometer, the lens transmitted virtually no light atwavelengths less than 650 nm.

[0602] The sunglass lens of this example was cured using activatinglight even though the lens forming composition includedultraviolet/visible absorbing fixed pigments. Since such fixed pigmentstend to absorb a portion of the activating light strongly, theactivating light might not have penetrated to the depths of the lensforming composition. The lens forming composition, however, contained aco-initiator in conjunction with a photoinitiator to help promote thecuring of the entire lens forming composition. The present example thusdemonstrates that a sunglass lens containing ultraviolet/visible lightabsorbing fixed pigments may be cured using activating light, whichincludes ultraviolet/visible light, to initiate polymerization of a lensforming composition that contains a photoinitiator/co-initiator system.

Example 13 Altering the Activated color of a Photochromic Lens

[0603] According to a preferred embodiment, a polymerizable mixture ofPRO-629 (see above for a description of the components of PRO-629),fixed pigments, a photoinitiator/co-initiator, and two photochromiccompounds was prepared in a manner similar to that described in Example12. The resulting lens forming composition includes PRO-629, and thefollowing components: Material amount IRG-184   80 ppm IRG 819  280 ppmCN-384  1.0% CN-386  1.0% Thermoplast Blue 0.67 ppm Thermoplast Red 0.04ppm Reversacol Sea Green  300 ppm Reversacol Berry Red  600 ppm

[0604] After the lens forming composition was prepared, a variety oflight effectors were added to the lens forming composition describedabove. The modified lens forming composition was then placed within amold cavity, prepared as described in Example 12.

[0605] Both sides of the mold assembly was irradiated with two doses ofactinic light (e.g., light having a wavelength above about 380 nm). Thefirst dose was applied for between 20 to 40 seconds. The final dose wasapplied for about 5 minutes. The resulting lens was demolded and treatedwith additional actinic light in a post-cure unit. The formed lens wasexposed to sunlight and the activated color of the lens observed. Thefollowing table summarizes the results when MEHQ, Tinuvin 400, ITX andIRG-369 are used as light effectors. S9 represents a lens formed withoutany added light effectors. EFFECTOR UV ACTIVATED SAMPLE EFFECTOR AMOUNTABSORBANCE COLOR S9  None — — Gray S10 MEHQ  350 ppm 294-317 nm BrownS11 Tinuvin 400 1130 ppm 295-390 nm Aqua-Green S12 ITX  500 ppm 280-415nm Yellow-Green S13 IRG-369  300 ppm 290-390 nm Green

[0606] The activated color of the formed lens was noted after exposingthe formed lens to sunlight. The presence of light effectors can have asignificant effect on the color of the lens. It should be noted thatthis change in color may be obtained without altering the relative ratioof the photochromic compounds (i.e., Berry Red and Sea Green). MEHQwhich exhibits absorption in the low ultraviolet light region tends toshift the color of the lens toward red, thus causing the lens to take ona brown color when exposed to sunlight. The absorbers Tinuvin 400, ITXand IRG-369 all tend to produce lenses having various green shades.Because of the broad photochromic activating light absorbance range ofthese compounds they may be effecting the photochromic activity of bothphotochromic compounds.

[0607] The above examples represent specific examples of how anactivated color of a lens may be altered by the addition of a lighteffector to a lens forming composition. By running similar studies withother light effectors, the activated color of a lens may be adjusted toa variety of different colors (e.g., red, orange, yellow, green, blue,indigo, or violet) without changing the nature of the photochromiccompounds.

[0608] Further modifications and alternative embodiments of variousaspects of the invention will be apparent to those skilled in the art inview of this description. Accordingly, this description is to beconstrued as illustrative only and is for the purpose of teaching thoseskilled in the art the general manner of carrying out the invention. Itis to be understood that the forms of the invention shown and describedherein are to be taken as the presently preferred embodiments. Elementsand materials may be substituted for those illustrated and describedherein, parts and processes may be reversed, and certain features of theinvention may be utilized independently, all as would be apparent to oneskilled in the art after having the benefit of this description of theinvention. Changes may be made in the elements described herein withoutdeparting from the spirit and scope of the invention as described in thefollowing claims.

What is claimed is:
 1. An apparatus for preparing an eyeglass lens,comprising: a first mold member having a casting face and a non-castingface; a second mold member having a casting face and a non-casting face,the second mold member being spaced apart from the first mold memberduring use such that the casting faces of the first mold member and thesecond mold member at least partially define a mold cavity; a coatingunit for applying a coating to at least one of the mold members or theeyeglass lens during use; and a lens curing unit configured to directactivating light toward the mold members during use; wherein the lenscuring unit and the coating unit are substantially contained within asingle enclosure.
 2. The apparatus of claim 1, wherein the apparatus isconfigured to form non-photochromic lenses and photochromic lenses. 3.The apparatus of claim 1, wherein the apparatus is configured tosubstantially simultaneously apply a coating to the first and secondmold members disposed within the coating unit and direct activatinglight toward another pair of mold members disposed within the lenscuring unit.
 4. The apparatus of claim 1, wherein the coating unit is aspin coating unit.
 5. The apparatus of claim 4, wherein the spin coatingunit comprises: a holder for holding the eyeglass lens or at least oneof the mold members, wherein the holder is configured to revolve duringuse; and an activating light source configured to direct activatinglight towards the coating unit during use.
 6. The apparatus of claim 5,wherein the holder is configured to revolve such that coating materialis radially dispersed during use.
 7. The apparatus of claim 5, whereinthe activating light source is an ultraviolet light source.
 8. Theapparatus of claim 5, wherein the activating light source has a peaklight intensity at a range of about 200 nm to about 300 nm.
 9. Theapparatus of claim 5, wherein the activating light source comprises asubstantially linear light element.
 10. The apparatus of claim 5,wherein the holder is configured to rotate up to about 1500 revolutionsper minute.
 11. The apparatus of claim 1, further comprising a cover forcovering the coating unit, wherein an activating light source for usewith the coating unit is positioned on an inner surface of the cover.12. The apparatus of claim 1, wherein the lens curing unit comprises afirst light source configured to generate and direct activating lighttoward at least one of the mold members during use.
 13. The apparatus ofclaim 12, wherein the first light source is configured to directactivating light toward the first mold member, and wherein the lenscuring unit further comprises a second light source configured togenerate and direct activating light toward the second mold member. 14.The apparatus of claim 13 wherein the first and second light sources areconfigured to generate and direct a pulses of activating light towardthe mold members.
 15. The apparatus of claim 12, further comprising afilter disposed directly adjacent to at least one of the mold members,the filter being configured to manipulate ail intensity of theactivating light directed toward the mold members during use.
 16. Theapparatus of claim 15, wherein the filter is a hazy filter comprising avarying thickness such that the filter varies an intensity distributionof activating light directed across the mold members during use.
 17. Theapparatus of claim 15, wherein the filter is a liquid crystal displayfilter.
 18. The apparatus of claim 12, further comprising an airdistributor configured to apply air to the mold members during use. 19.The apparatus of claim 12, wherein the first light source comprises afluorescent light source configured to emit light at a wavelength ofabout 385 nanometers to 490 nanometers.
 20. The apparatus of claim 12,wherein the lens curing unit comprises a lens drawer for positioning themold members proximate to the first light source, the lens drawer beingconfigurable to be inserted within and removed from the irradiationchamber.
 21. The apparatus of claim 1, further comprising a post-cureunit, the post-cure unit configured to simultaneously apply heat andactivating light to the interior of the post-cure unit.
 22. Theapparatus of claim 21, wherein the post-cure unit comprises afluorescent light.
 23. The apparatus of claim 21, wherein the post-curecomprises a heater, the heater configured to heat the interior of thepost-cure unit to a temperature of up to about 125° C.
 24. The apparatusof claim 21, wherein the post-cure unit comprises a conductive heatingapparatus, the conductive heating apparatus being adapted toconductively apply heat to a face of at least one of the mold membersduring use.
 25. The apparatus of claim 1, further comprising aprogrammable controller configured to substantially simultaneouslycontrol operation of the coating unit and the lens curing unit duringuse.
 26. The apparatus of claim 1, further comprising a programmablecontroller configured to adjust a dose of the activating light reachingthe mold member as a function of the temperature of the mold members.27. The apparatus of claim 1, further comprising a programmablecontroller configured to vary an intensity of the light as a function ofthe temperature of the molds.
 28. The apparatus of claim 1, furthercomprising a programmable controller configured to control operation ofthe lens curing unit using a Proportional-Integral-Derivative controlscheme.
 29. The apparatus of claim 1, further comprising a programmablecontroller and a light sensor configured to measure the dose of lighttransmitted to the mold cavity, and wherein the light sensor isconfigured to communicate with the programmable controller, and whereinthe programmable controller varies the intensity or duration of lightsuch that a predetermined dose is transmitted to the mold cavity. 30.The apparatus of claim 1, wherein the lens curing unit comprises a firstlight source and a second light source, and further comprising aprogrammable controller configured to individually control the first andsecond lights.
 31. The apparatus of claim 1, further comprising acooling fan for cooling the mold members during use and a thermocouplefor measuring a temperature of the mold members during use, and furthercomprising a programmable controller configured to operate the coolingfan in response to the temperature of the mold members as measured bythe thermocouple.
 32. The apparatus of claim 1, wherein the coating unitis a spin-coating unit, and further comprising a programmable controllerconfigured to control a rate of rotation of a holder of the spin coatingunit.
 33. The apparatus of claim 1, further comprising a post-cure unit,the post-cure unit configured to simultaneously apply heat andactivating light to the interior of the post-cure unit, and furthercomprising a programmable controller configured to substantiallysimultaneously operate the coating unit, the lens curing unit, and thepost-cure unit.
 34. The apparatus of claim 1, further comprising aprogrammable controller configured to control operation of the lenscuring unit as a function of the eyeglass lens prescription.
 35. Theapparatus of claim 1, further comprising a liquid crystal displaypositioned between an activating light source and one of the moldmembers, and further comprising a programmable controller configured tochange the filter in response to the prescription of the eyeglass lens.36. An apparatus for preparing an eyeglass lens, comprising: a firstmold member having a casting face and a non-casting face; a second moldmember having a casting face and a non-casting face, the second moldmember being spaced apart from the first mold member during use suchthat the casting faces of the first mold member and the second moldmember at least partially define a mold cavity; a lens curing unitconfigured to direct activating light toward the mold members duringuse; and a post-cure unit configured to apply heat and activating lightto the eyeglass lens.
 37. An apparatus for curing an eyeglass lens,comprising: a first mold member having a casting face and a non-castingface; a second mold member having a casting face and a non-casting face,the second mold member being spaced apart from the first mold memberduring use such that the casting faces of the first mold member and thesecond mold member at least partially define a mold cavity; a coatingunit configured for applying a coating to at least one of the moldmembers or the eyeglass lens during use; a lens curing unit configuredto direct activating light toward the mold members during use; apost-cure unit configured to apply heat and activating light to theeyeglass lens; and a programmable controller configured to substantiallysimultaneously control operation of the coating unit, the lens curingunit, and the post-cure unit during use.
 38. A system for preparing aneyeglass lens, comprising: a first mold member having a casting face anda non-casting face; a second mold member having a casting face and anon-casting face, the second mold member being adapted to be spacedapart from the first mold member during use such that the casting facesof the fist mold member and the second mold member at least partiallydefine a mold cavity; a lens forming composition adapted to be disposedwithin the mold cavity during use, comprising: a monomer that cures byexposure to activating light to form the eyeglass lens during use; aphotoinitiator that initiates curing of the monomer in response to beingexposed to activating light during use; a coating unit for applying acoating to at least one of the mold members or the eyeglass lens duringuse; and a lens curing unit configured to cure at least a portion of alens forming composition into the eyeglass lens by directing activatinglight toward mold members during use.
 39. The system of claim 38,wherein the lens forming composition further comprises photochromiccompounds.
 40. The system of claim 38, wherein the lens formingcomposition further comprises ultraviolet/visible light absorbingcompounds.
 41. The system of claim 38, wherein the apparatus isconfigured to substantially simultaneously apply a coating to a firstset of mold members and direct activating light toward a second set ofmold members.
 42. The system of claim 38, wherein the coating unit is aspin coating unit.
 43. The system of claim 42, wherein the spin coatingunit comprises: a holder for holding the eyeglass lens or at least oneof the mold members, wherein the holder is configured to revolve duringuse; and an activating light source configured to direct activatinglight towards the coating material during use.
 44. The system of claim43, wherein the holder is configured to revolve such that coatingmaterial is radially dispersed during use.
 45. The system of claim 43,wherein the activating light source is an ultraviolet light source. 46.The system of claim 43, wherein the activating light source has a peaklight intensity at a range of about 200 nm to about 300 nm.
 47. Thesystem of claim 43, wherein the activating light source comprises asubstantially linear light element.
 48. The system of claim 43, whereinthe holder is configured to rotate up to about 1500 revolutions perminute.
 49. The system of claim 38, further comprising a cover forcovering the coating unit, wherein an activating light source for usewith the coating unit is positioned on an inner surface of the cover.50. The system of claim 38, wherein the lens curing unit comprises afirst light source configured to generate and direct activating lighttoward at least one of the mold members during use.
 51. The system ofclaim 50, wherein the first light source is configured to directactivating light toward the first mold member, and wherein the lenscuring unit further comprises a second light source configured togenerate and direct activating light toward the second mold member. 52.The system of claim 50, further comprising a filter disposed directlyadjacent to at least-one of the mold members, the filter beingconfigured to manipulate an intensity of the activating light directedtoward the mold members during use.
 53. The system of claim 52, whereinthe filter is a hazy filter comprising a varying thickness such that thefilter varies an intensity distribution of activating light directedacross the mold members during use.
 54. The system of claim 52, whereinthe filter is a liquid crystal display filter.
 55. The system of claim38, further comprising an air distributor configured to apply air to themold cavity to remove heat from the mold cavity during use.
 56. Thesystem of claim 50, wherein the first light source comprises afluorescent light source configured to emit light at a wavelength ofabout 385 nanometers to 490 nanometers.
 57. The system of claim 38,further comprising a post-cure unit, the post-cure unit configured tosimultaneously apply heat and activating light to the interior of thepost-cure unit.
 58. The system of claim 57, wherein the post-cure unitcomprises a fluorescent light.
 59. The system of claim 57, wherein thepost-cure unit comprises a heater, the heater configured to heat theinterior of the post-cure unit to a temperature of up to about 125° C.60. The system of claim 38, further comprising a programmable controllerconfigured to substantially simultaneously control operation of thecoating unit and the lens curing unit during use.
 61. The system ofclaim 38, further comprising a programmable controller configured toadjust a dose of the activating light reaching the mold member as afunction of the temperature of the mold members.
 62. The system of claim38, further comprising a programmable controller configured to vary anintensity of the light as a function of the difference in thetemperature of the molds over a period of time.
 63. The system of claim38, further comprising a programmable controller configured to controloperation of the lens curing unit using aProportional-Integral-Derivative control scheme.
 64. The system of claim38, further comprising a programmable controller and a light sensorconfigured to measure the dose of light transmitted to the mold cavity,wherein the light sensor is configured to communicate with theprogrammable controller, and wherein the programmable controller variesthe intensity or duration of light such that a predetermined dose istransmitted to the mold cavity.
 65. The system of claim 38, wherein thelens curing unit comprises a first light source and a second lightsource, and further comprising a programmable controller configured toindividually control the first and second lights.
 66. The system ofclaim 38, further comprising a cooling fan for cooling the mold membersduring use, a thermocouple for measuring a temperature of the moldmembers during use, and a programmable controller configured to operatethe cooling fan in response to the temperature of the mold members. 67.The system of claim 38, wherein the coating unit is a spin-coating unit,and further comprising a programmable controller configured to control arate of rotation of a holder of the spin coating unit.
 68. The system ofclaim 38, further comprising a post-cure unit, the post-cure unitconfigured to simultaneously apply heat and activating light to theinterior of the post-cure unit, and a programmable controller configuredto substantially simultaneously operate the coating unit, the lenscuring unit, and the post-cure unit.
 69. The system of claim 38, furthercomprising a programmable controller configured to control operation ofthe lens curing unit as a function of the eyeglass lens prescription.70. The system of claim 38, further comprising a liquid crystal displaypositioned between an activating light source and one of the moldmembers, and a programmable controller configured to change the liquidcrystal display in response to the prescription of the eyeglass lens.71. The system of claim 38, wherein the monomer comprises an aromaticcontaining bis(allyl carbonate)-functional monomer.
 72. A system forpreparing an eyeglass lens, comprising: a first mold member having acasting face and a non-casting face; a second mold member having acasting face and a non-casting face, the second mold member beingadapted to be spaced apart from the first mold member during use suchthat the casting faces of the first mold member and the second moldmember at least partially define a mold cavity; a lens formingcomposition adapted to be disposed within the mold cavity during use,comprising: a monomer that cures by exposure to activating light to formthe eyeglass lens during use; a photoinitiator that initiates curing ofthe monomer in response to being exposed to activating light during use;a lens curing unit configured to cure at least a portion of a lensforming composition into the eyeglass lens by directing activating lighttoward mold members during use; and a post-cure unit configured to applyheat and activating light to the eyeglass lens to substantially completecuring of the eyeglass lens during use.
 73. The system of claim 72,wherein the lens forming composition further comprises photochromiccompounds.
 74. The system of claim 72, wherein the lens formingcomposition further comprises ultraviolet/visible light absorbingcompounds.
 75. A system for preparing an eyeglass lens, comprising: afirst mold member having a casting face and a non-casting face; a secondmold member having a casting face and a non-casting face, the secondmold member being adapted to be spaced apart from the first mold memberduring use such that the casting faces of the first mold member and thesecond mold member at least partially define a mold cavity; a lensforming composition adapted to be disposed within the mold cavity duringuse, comprising: a monomer that cures by exposure to activating light toform the eyeglass lens during use; a photoinitiator that initiatescuring of the monomer in response to being exposed to activating lightduring use; a coating unit configured to produce a coating on at leastone of the mold members or the eyeglass lens during use; a lens curingunit configured to cure at least a portion of a lens forming compositioninto the eyeglass lens by directing activating light toward mold membersduring use; a post-cure unit configured to apply heat and activatinglight to the eyeglass lens to substantially complete curing of theeyeglass lens during use; and a programmable controller configured tosubstantially simultaneously control operation of the coating unit, thelens curing unit, and the post-cure unit during use.
 76. The system ofclaim 75, wherein the lens forming composition further comprisesphotochromic compounds.
 77. The system of claim 75, wherein the lensforming composition further comprises ultraviolet/visible lightabsorbing compounds.
 78. A programmable logic controller for controllinga lens forming apparatus, the lens forming apparatus comprising: a firstmold member having a casting face and a non-casting face; a second moldmember having a casting face and a non-casting face, the second moldmember being spaced apart from the first mold member during use suchthat the casting faces of the first mold member and the second moldmember at least partially define a mold cavity; a coating unitconfigured to produce a coating on at least one of the mold members orthe eyeglass lens during use; and a lens curing unit configured todirect activating light toward the mold members during use; wherein thecontroller is configured to control the operation of the lens curingunit.
 79. The controller of claim 78, wherein the controller isconfigured to substantially simultaneously control the operation of thecoating unit and the lens curing unit.
 80. The controller of claim 79,wherein the coating unit is a spin coating unit, and wherein thecontroller is configured to control the rotation of the holder duringuse.
 81. The controller of claim 78, wherein the coating unit comprisesa light source, and wherein the controller is configured to control thelight source during use.
 82. The controller of claim 78, wherein thecontroller is configured to measure the ambient room temperature, andwherein the controller is configured to determine the appropriate doseof light required to cure the lens forming composition, based on theambient room temperature.
 83. The controller of claim 78, wherein thecontroller is configured to adjust a dose of the activating lightreaching the mold member as a function of the temperature of the moldmembers.
 84. The controller of claim 78, wherein the controller isconfigured to vary an intensity of the light as a function of thedifference in the temperature of the molds over a period of time. 85.The controller of claim 78, wherein the controller is configured tocontrol operation of the lens curing unit using aProportional-Integral-Derivative control scheme.
 86. The controller ofclaim 78, wherein the apparatus further comprises a light sensorconfigured to measure the dose of light transmitted to the mold cavity,and wherein the light sensor is configured to communicate with thecontroller, and wherein the controller varies the intensity or durationof light such that a predetermined dose is transmitted to the moldcavity.
 87. The controller of claim 78, wherein the lens curing unitcomprises a first light source and a second light source, and whereinthe control unit is configured to individually control the first andsecond light sources.
 88. The controller of claim 78, wherein theapparatus further comprises a cooling fan for cooling the mold membersduring use and a sensor for measuring a temperature of the mold membersduring use, and wherein the controller is configured to operate thecooling fan in response to the temperature of the mold members.
 89. Thecontroller of claim 78, wherein the controller is configured todetermine when a lens curing process is complete by monitoring atemperature response of a lens forming composition during theapplication of activating light.
 90. The controller of claim 78, furthercomprising a post-cure unit, the post-cure unit configured tosimultaneously apply heat and activating light to the interior of thepost-cure unit, and wherein the controller is configured tosubstantially simultaneously operate the coating unit, the lens curingunit, and the post-cure unit.
 91. The controller of claim 78, whereinthe control unit is configured to control operation of the lens curingunit as a function of the eyeglass lens prescription.
 92. The controllerof claim 78, further comprising a liquid crystal display positionedbetween an activating light source and one of the mold members, andwherein the controller is configured to change the liquid crystaldisplay in response to the prescription of the eyeglass lens.
 93. Thecontroller of claim 78, wherein the controller is configured to performsystem-diagnostic checks.
 94. The controller of claim 78, wherein thecontroller is configured to notify the user when the system requiresmaintenance.
 95. The controller of claim 78, wherein the controller isconfigured to display instructions for the operator during a lensforming process.
 96. A programmable logic controller for controlling alens forming apparatus, the lens forming apparatus comprising: a firstmold member having a casting face and a non-casting face; a second moldmember having a casting face and a non-casting face, the second moldmember being spaced apart from the first mold member during use suchthat the casting faces of the first mold member and the second moldmember at least partially define a mold cavity; a coating unitconfigured to produce a coating on at least one of the mold members orthe eyeglass lens during use; a lens curing unit configured to directactivating light toward the mold members during use; and a post-cureunit configured to apply heat and activating light to the eyeglass lens;wherein the programmable logic controller is configured to substantiallysimultaneously control the operation of the coating unit, the lenscuring unit, and the post-cure unit.
 97. A gasket configured to engage afirst mold set for forming a first lens of a first power, the gasketcomprising at least four discrete projections for spacing mold membersof a mold set, and wherein the projections are arranged on an interiorsurface of the gasket.
 98. The gasket of claim 97, wherein the at leastfour discrete projections are evenly spaced around the interior surfaceof the gasket.
 99. The gasket of claim 97, wherein the at least fourdiscrete projections are spaced at about 90 degree increments around theinterior surface of the gasket.
 100. The gasket of claim 97, wherein thegasket is configured to engage a second mold set for forming a secondlens of a second power.
 101. The gasket of claim 97, wherein the gasketcomprises a fill port for receiving a lens forming composition while thegasket is fully engaged to a mold set.
 102. The gasket of claim 101,wherein the gasket further comprises an interior surface and an exteriorsurface, and wherein the fill port extends from the interior surface ofthe gasket to the exterior surface.
 103. An assembly for making plasticprescription lenses, comprising: a first mold set for forming a firstlens of a first power, the first mold set comprising a front mold memberand a back mold member; a gasket for engaging the first mold set, thegasket comprising at least four discrete projections for spacing thefront mold member from the back mold member; and wherein the front moldmember, the back mold member, and the gasket at least partially define amold cavity for retaining a lens forming composition.
 104. The assemblyof claim 103, wherein the back mold member comprises a steep axis and aflat axis, and wherein each of the at least four discrete projectionsforms an oblique angle with the steep axis and the flat axis of the backmold member.
 105. The assembly of claim 103, wherein the back moldmember comprises a steep axis and a flat axis, and wherein each of theat least four discrete projections forms an about 45 degree angle withthe steep axis and the flat axis of the back mold member.
 106. Theassembly of claim 103, wherein the gasket is configured to engage asecond mold set for forming a second lens of a second power.
 107. Theassembly of claim 103, wherein the gasket further comprises a fill portfor receiving a lens forming composition while the gasket is fullyengaged to the mold set.
 108. A method for making a plastic eyeglasslens, comprising: engaging a gasket with a first mold set for forming afirst lens of a first power, wherein the first mold set comprises afront mold member and a back mold member, and wherein the front moldmember, the back mold member, and the gasket at least partially define amold cavity for retaining a lens forming composition, and wherein thegasket comprises at least four discrete projections arranged on aninterior surface thereof for spacing the first and second mold members;introducing a lens forming composition into the mold cavity; and curingthe lens forming composition.
 109. The method of claim 108, wherein theback mold member comprises a steep axis and a flat axis, and whereinengaging a gasket with a first mold set comprises positioning the firstand second mold members such that the at least four discrete projectionseach form an oblique projection angle with the steep axis and the flataxis of the back mold member.
 110. The method of claim 108, wherein theback mold member comprises a steep axis and a flat axis, and whereinengaging a gasket with a first mold set comprises positioning the backmold member such that the at least four discrete projections each forman about 45 degree projection angle with the steep axis and the flataxis of the back mold member.
 111. The method of claim 108, furthercomprising: removing the first mold set from the gasket; and engagingthe gasket with a second mold set for forming a second lens of a secondpower.
 112. The method of claim 108, wherein the gasket furthercomprises a fill port for receiving a lens forming composition while thegasket is fully engaged to a mold set.
 113. The method of claim 112,wherein the fill port extends from an interior surface to an exteriorsurface of the gasket.
 114. A method of forming a non-photochromic lensunder photochromic lens forming conditions comprising: placing a liquidlens forming composition in a mold cavity defined by at least a firstmold member and a second mold member, the lens forming compositioncomprising: a monomer that cures by exposure to activating light to formthe eyeglass lens during use; an ultraviolet/visible light absorbingcompound; a co-initiator that activates curing of the monomer to formthe eyeglass lens during use; and a photoinitiator that is activatedupon exposure to activating light; and directing activating light towardthe mold cavity, wherein the photoinitiator activates the co-initiatorin response to being exposed to the activating light during use, andwherein activation of the co-initiator causes the lens formingcomposition to at least partially cure to form a non-photochromic lensduring use.
 115. The method of claim 114, further comprising applying ahydrophobic coat to the eyeglass lens, wherein the hydrophobic coatingis adapted to inhibit the eyeglass lens from being exposed to water andto ambient oxygen.
 116. The method of claim 114, wherein the first moldmember comprises a casting face and a non-casting face, and furthercomprising placing a first hardcoat layer upon said casting face and asecond hard coat layer upon said first hardcoat layer prior to placingthe liquid lens forming composition in the mold cavity.
 117. The methodof claim 114, wherein the eyeglass lens is formed from the lens formingcomposition in a time period of less than about 30 minutes.
 118. Themethod of claim 114, further comprising placing a filter substantiallyadjacent to at least one of the mold members, wherein the filtercomprises a varying thickness such that the filter varies an intensitydistribution of the activating light directed across the mold members.119. The method of claim 114, further comprising placing a filtersubstantially adjacent to at least one of the mold members, wherein thefilter comprises a varying transmissivity such that the filter varies anintensity distribution of the activating light directed across the moldmembers.
 120. The method of claim 114, wherein the monomer comprises apolyethylenic-functional monomer containing ethylenically unsaturatedgroups selected from acrylyl or methacrylyl.
 121. The method of claim114, wherein the photoinitiator forms a first polymer chain radical inresponse to being exposed to activating light, and wherein the firstpolymer chain radical reacts with the co-initiator, thereby forming asecond polymer chain radical.
 122. The method of claim 114, wherein theactivating light has a wavelength in the range of about 380 to about 490nanometers.
 123. A filter for use in a lens forming apparatus, thefilter comprising a liquid crystal display panel, positionable betweenan activating light source for producing activating light and a moldassembly, wherein the liquid crystal display is configured to vary anintensity of activating light when the activating light is directedtoward the mold assembly.
 124. The filter of claim 123, wherein theliquid crystal display panel is configured to produce a pattern of lightand dark areas, wherein the dark areas reduce the intensity of theactivating light reaching the mold assembly to a greater extent than thelight areas.
 125. The filter of claim 123, wherein the liquid crystaldisplay panel is configured to produce a pattern of light and darkareas, and wherein the liquid crystal display panel is furtherconfigured to allow the pattern to be altered during a curing cycle.126. The filter of claim 123, wherein the liquid crystal display panelis configured to produce a predetermined pattern of light and dark area,the predetermined pattern being selected based on a prescription of alens defined by the mold assembly.
 127. The filter of claim 123, whereinthe liquid crystal display panel is configured to become substantiallyentirely darkened, such that the activating light is substantiallyinhibited from reaching the mold assembly.
 128. The filter of claim 123,wherein the liquid crystal display panel is configured to be alternatedbetween a transmissive state and a darkened state, such that pulses ofactivating light are directed toward the mold members.
 129. The filterof claim 123, wherein the lens forming apparatus further comprises anadditional mold assembly, and wherein the liquid crystal display panelis positioned between the activating light source and the additionalmold assembly, and wherein the liquid crystal display panel isconfigured to produce a first pattern of light and dark areas betweenthe activating light source and the mold assembly, and wherein theliquid crystal display panel is configured to produce a second patternof light and dark areas between the activating light source and theadditional mold assembly.
 130. The filter of claim 129, wherein thefirst and second patterns are independently variable during a curingcycle.
 131. The filter of claim 123, wherein the liquid crystal displaypattern is configured to be connected to a controller, the controllerbeing configured to alter a pattern of light and dark areas displayed onthe liquid crystal display panel in response to lens curing conditions.132. A method of forming a plastic eyeglass lens comprising: placing aliquid lens forming composition in a mold cavity defined by at least afirst mold member and a second mold member, the lens forming compositioncomprising: a monomer that cures by exposure to activating light to formthe eyeglass lens during use; a photoinitiator that initiates curing ofthe monomer in response to being exposed to activating light during use;directing activating light toward the mold cavity, the activating lightcausing the lens forming composition to at least partially cure; andfiltering the activated light with a filter, the filter comprising aliquid crystal display panel, wherein the liquid crystal display panelis configured to vary an intensity of activating light as the activatinglight is directed toward the mold members.
 133. The method of claim 132,wherein filtering the activated light comprises forming a pattern oflight and dark areas on the liquid crystal display panel, wherein thedark areas reduce the intensity of the activating light reaching themold assembly to a greater extent than the light areas.
 134. The methodof claim 133, further comprising altering the pattern while light isdirected toward the mold cavity.
 135. The method of claim 132, whereinfiltering the activated light comprises forming a predetermined patternof light and dark areas on the liquid crystal display panel, thepredetermined pattern being selected based on a prescription of a lensdefined by the mold cavity.
 136. The method of claim 132, whereinfiltering the activated light comprises substantially darkening thepotion of the liquid crystal display panel between the mold cavity andthe activating light, such that the activating light is substantiallyinhibited from reaching the mold assembly.
 137. The method of claim 132,wherein filtering the activated light comprises alternating the liquidcrystal display panel between a transmissive state and a darkened statesuch that pulses of activating light are directed toward the moldmembers.
 138. The method of claim 132, wherein filtering the activatinglight comprises producing a pattern of light and dark areas on theliquid crystal display panel and altering the pattern in response tolens curing conditions.
 139. The method of claim 132, wherein thealtering of the pattern is performed by a controller coupled to theliquid crystal display panel.
 140. A composition curable by exposure toactivating light to form a photochromic plastic eyeglass lens, thecomposition comprising: a monomer that cures by exposure to activatinglight to form the eyeglass lens during use; a photoinitiator thatinitiates curing of the monomer in response to being exposed toactivating light during use; a first photochromic composition adapted,when cured in an eyeglass lens and subsequently exposed to photochromicactivating light during use, to exhibit a first color; a secondphotochromic composition adapted, when cured in an eyeglass lens andsubsequently exposed to photochromic activating light during use, toexhibit a second color; a light effector composition, wherein the lighteffector composition is adapted to affect the activated color of thephotochromic plastic eyeglass lens such that the photochromic plasticeyeglass lens, when exposed to photochromic activating light,selectively exhibits the first color, the second color, or a third colorduring use.
 141. The composition of claim 140, wherein the lighteffector composition selectively affects the absorptivity of the firstphotochromic composition or the second photochromic composition to causethe eyeglass lens, when exposed to photochromic activating light, toexhibit a predetermined color.
 142. The composition of claim 140,wherein the light effector composition selectively affects theabsorptivity of the first photochromic composition and the secondphotochromic composition to cause the eyeglass lens, when exposed tophotochromic activating light, to exhibit a predetermined color. 143.The composition of claim 140, wherein the light effector compositioncomprises a photoinitiator.
 144. The composition of claim 140, whereinthe light effector composition comprises a non-photochromicultraviolet/visible light absorber.
 145. The composition of claim 140,wherein the light effector composition comprises a non-photochromic dye.146. The composition of claim 140, wherein the light effectorcomposition comprises an ultraviolet light stabilizer.
 147. Thecomposition of claim 140, wherein the first and second photochromiccompositions comprise a spirooxazine, a spiropyran, aspironaphthoxazine, a spiropyridobenzoxazine, a spirobenzoxazine, anapthopyran, a benzopyran, a spironapthopyran, anindolinospironapthoxazine, an indolinospironapthopyran, adiarylnapthopyran, an organometallic, or a phenylmercury.
 148. Thecomposition of claim 140, wherein the monomer comprises apolyethylenic-functional monomer containing ethylenically unsaturatedgroups selected from acrylyl or methacrylyl.
 149. The composition ofclaim 140, wherein the monomer comprises an aromatic containingbis(allyl carbonate)-functional monomer.
 150. The composition of claim140, wherein the first photochromic composition comprises Reversacol SeaGreen and the second photochromic composition comprises Reversacol BerryRed.
 151. The composition of claim 150, wherein the light effectorcomposition comprises monomethylether hydroquinone, and wherein theeyeglass lens, when exposed to photochromic activating light,selectively exhibits a brown color.
 152. The composition of claim 150,wherein the light effector composition comprises a mixture of2-[4-((2-hydroxy-3-dodecyloxypropyl)-oxy)-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazineand2-[4-((2-hydroxy-3-tridecyloxypropyl)-oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl-1,3,5-triazine,and wherein the eyeglass lens, when exposed to photochromic activatinglight, selectively exhibits an aqua-green color.
 153. The composition ofclaim 150, wherein the light effector composition comprises2-isopropyl-thioxanthone, and wherein the eyeglass lens, when exposed tophotochromic activating light, selectively exhibits a yellow-greencolor.
 154. The composition of claim 150, wherein the light effectorcomposition comprises2-benzyl-2-N,N-dimethylamino-1-(4-morpholinophenyl)-1-butanone, andwherein the eyeglass lens, when exposed to photochromic activatinglight, selectively exhibits a green color.
 155. A composition curable byexposure to activating light to form a photochromic plastic eyeglasslens, the composition comprising: a monomer that cures by exposure toactivating light to form the eyeglass lens during use; a photoinitiatorthat initiates curing of the monomer in response to being exposed toactivating light during use; a first photochromic composition adapted,when cured in an eyeglass lens and subsequently exposed to photochromicactivating light during use, to exhibit a first color; a secondphotochromic composition adapted, when cured in an eyeglass lens andsubsequently exposed to photochromic activating light during use, toexhibit a second color; a light effector composition, wherein the lighteffector composition is adapted to affect the activated color of thephotochromic plastic eyeglass lens such that the photochromic plasticeyeglass lens, when exposed to photochromic activating light,selectively exhibits a third color which substantially differs from thefirst and second colors during use.
 156. A composition curable byexposure to activating light to form a photochromic plastic eyeglasslens, the composition comprising: a monomer composition comprising anaromatic containing bis(allyl carbonate)-functional monomer; aco-initiator composition configured to activate curing of the monomercomposition to form the eyeglass lens during use comprising an acrylatedamine; and a photoinitiator configured to activate the co-initiatorcomposition in response to being exposed to activating light during use;and a dye composition adapted to, when cured in an eyeglass lens, causethe eyeglass lens to exhibit a second color; and wherein the dyecomposition acts as a light effector composition on the photochromiccomposition such that the photochromic activity of the photochromiccompound is reduced, and wherein a color of the photochromic plasticeyeglass lens, when exposed to activating light, exhibits a third color.157. A method of altering an activated color of a photochromic lenscomprising: mixing a first photochromic composition adapted, when curedin an eyeglass lens and subsequently exposed to photochromic activatinglight during use, to exhibit a first color, with a second photochromiccomposition adapted, when cured in an eyeglass lens and subsequentlyexposed to photochromic activating light during use, to exhibit a secondcolor, to form a first polymerizable lens forming composition; adding alight effector composition to the polymerizable lens forming compositionto form a second polymerizable lens forming composition; and curing thesecond polymerizable lens forming composition to form an eyeglass lens;wherein the activated color of the eyeglass lens differs from anactivated color of an eyeglass lens formed from the first polymerizablelens forming composition.
 158. A kit for preparing a composition curableby exposure to activating light to form a photochromic plastic eyeglasslens, the kit comprising: a base composition comprising: a monomer thatcures by exposure to activating light to form the eyeglass lens duringuse; and a photoinitiator that initiates curing of the monomer inresponse to being exposed to activating light during use; a firstphotochromic composition adapted, when cured in an eyeglass lens andsubsequently exposed to photochromic activating light during use, toexhibit a first color; a second photochromic composition adapted, whencured in an eyeglass lens and subsequently exposed to photochromicactivating light during use, to exhibit a second color; at least twolight effector compositions; wherein a first light effector compositionis adapted, when mixed with the first photochromic composition, thesecond photochromic composition, and the base composition, and aftersuch mixture is cured to form an eyeglass lens, to affect the activatedcolor of the eyeglass lens such that the eyeglass lens, when exposed tophotochromic activating light, selectively exhibits a third color duringuse; and wherein a second light effector composition is adapted, whenmixed with the first photochromic composition, the second photochromiccomposition, and the base composition, and after such mixture is curedto form an eyeglass lens, to affect the activated color of the eyeglasslens such that the eyeglass lens, when exposed to photochromicactivating light, selectively exhibits a fourth color during use.
 159. Alens forming composition curable upon exposure to activating light toform a plastic eyeglass lens, comprising: a monomer compositioncomprising an aromatic containing polyethylenic polyether functionalmonomer; and a photoinitiator configured to initiate polymerization ofthe monomer composition in response to being exposed to activating lightduring use.
 160. The lens forming composition of claim 159 wherein thearomatic containing polyethylenic polyether functional monomer comprisesan aromatic containing polyether polyethylenic functional monomercontaining at least one group selected from acrylyl or methacrylyl. 161.The lens forming composition of claim 159 wherein the aromaticcontaining polyethylenic polyether functional monomer comprises anethoxylated bisphenol A containing at least one group selected fromacrylyl or methacrylyl.
 162. The lens forming composition of claim 159wherein the aromatic containing polyethylenic polyether functionalmonomer comprises an ethoxylated bisphenol A di(meth)acrylate.
 163. Thelens forming composition of claim 159 wherein the aromatic containingpolyethylenic polyether functional monomer comprises ethoxylated 4bisphenol A dimethacrylate.
 164. The lens forming composition of claim159 wherein the monomer composition further comprises a polyethylenicfunctional monomer.
 165. The lens forming composition of claim 164wherein the polyethylenic functional monomer comprisestris(2-hydroxyethyl)isocyanurate triacrylate, ethoxylated 10 bisphenol Adimethacrylate, ethoxylated 4 bisphenol A dimethacrylate,dipentaerythritol pentaacrylate, 1,6-hexanediol dimethacrylate,isobornyl acrylate, bisphenol A bis allyl carbonate, pentaerythritoltriacrylate or mixtures thereof.
 166. The lens forming composition ofclaim 159 wherein the aromatic containing polyethylenic polyetherfunctional monomer comprises an ethoxylated bisphenol Adi(meth)acrylate, and wherein the monomer composition further comprisesa polyethylenic functional monomer.
 167. The lens forming composition ofclaim 159 wherein the aromatic containing polyethylenic polyetherfunctional monomer comprises an ethoxylated bisphenol Adi(meth)acrylate, and wherein the monomer composition further comprisesa polyethylenic functional monomer, and wherein the polyethylenicfunctional monomer comprises tris(2-hydroxyethyl)isocyanuratetriacrylate, ethoxylated 10 bisphenol A dimethacrylate, ethoxylated 4bisphenol A dimethacrylate, dipentaerythritol pentaacrylate,1,6-hexanediol dimethacrylate, isobornyl acrylate, bisphenol A bis allylcarbonate, pentaerythritol triacrylate or mixtures thereof.
 168. Thelens forming composition of claim 159, further comprising a co-initiatorcomposition, wherein the co-initiator composition comprises an amine.169. The lens forming composition of claim 159, further comprising aco-initiator composition, wherein the co-initiator composition comprisesan acrylyl amine.
 170. The lens forming composition of claim 159,further comprising a co-initiator composition, wherein the co-initiatorcomposition comprises an ethanol amine.
 171. The lens formingcomposition of claim 159, further comprising a co-initiator composition,wherein the co-initiator composition comprises an aromatic amine. 172.The lens forming composition of claim 159, further comprising aco-initiator composition, wherein the co-initiator composition comprisesan acrylyl amine, the acrylyl amine comprising monoacrylated amines,diacrylated amines, or mixtures thereof.
 173. The lens formingcomposition of claim 159, further comprising a co-initiator composition,wherein the co-initiator composition comprises CN 384 and CN-386. 174.The lens forming composition of claim 159, further comprising aco-initiator composition, wherein the co-initiator is an amine, andwherein an amount of the co-initiator composition in the lens formingcomposition ranges from about 500 ppm to about 7% by weight.
 175. Thelens forming composition of claim 159 wherein the photoinitiatorcomposition comprisesbis(2,6-dimethoxybenzoyl)-2,4,4-trimethylphenyl)phosphine oxide. 176.The lens forming composition of claim 159 wherein the photoinitiatorcomposition comprisesbis(2,6-dimethoxybenzoyl)-(2,4,4-trimethylphenyl)phosphine oxide and1-hydroxycyclohexylphenyl ketone.
 177. The lens forming composition ofclaim 159 wherein an amount of the photoinitiator composition in thelens forming composition ranges from about 50 ppm to about 0.5%. 178.The lens forming composition of claim 159 further comprising aco-initiator, wherein the photoinitiator composition comprisesbis(2,6-dimethoxybenzoyl)-(2,4,4-trimethylphenyl)phosphine oxide and2-isopropylthioxanthone.
 179. The lens forming composition of claim 159further comprising a co-initiator, wherein the photoinitiatorcomposition comprisesbis(2,6-dimethoxybenzoyl)-(2,4,4-trimethylphenyl)phosphine oxide. 180.The lens forming composition of claim 159 wherein the photoinitiatorcomposition comprisesbis(2,6-dimethoxybenzoyl)-(2,4,4-trimethylphenyl)phosphine oxide and2-isopropylthioxanthone.
 181. The lens forming composition of claim 159further comprising a co-initiator, wherein the photoinitiatorcomposition comprises 2-isopropylthioxanthone.
 182. The lens formingcomposition of claim 159, further comprising an activating lightabsorbing compound.
 183. The lens forming composition of claim 159,further comprising a photochromic compound.
 184. The lens formingcomposition of claim 159, further comprising a photochromic compound,and wherein the photochromic compound comprises a spirooxazine,spiropyrans, spironaphthoxazines, spiropyridobenzoxazines,spirobenzoxazines, napthopyrans benzopyrans, spironapthopyrans,indolinospironapthoxazines, indolinospironapthopyrans,diarylnapthopyrans, organometallic, or phenylmercury.
 185. The lensforming composition of claim 159, further comprising a photochromiccomposition, wherein the photochromic composition comprises Corn Yellow,Berry Red, Sea Green, Plum Red, Variacrol Yellow, Palatinate Purple,CH-94, Variacrol Blue D, Oxford Blue, CH-266 or mixtures thereof. 186.The lens forming composition of claim 159, further comprising aphotochromic compound, and wherein an amount of photochromic compound inthe lens forming composition ranges from about 50 ppm to about 1000 ppm.187. The lens forming composition of claim 159, further comprising anultraviolet absorbing compound for inhibiting at least a portion ofultraviolet light from being transmitted through the eyeglass lensduring use.
 188. The lens forming composition of claim 159, furthercomprising an ultraviolet absorbing compound for inhibiting at least aportion of ultraviolet light from being transmitted through the eyeglasslens during use, wherein the ultraviolet absorbing compound comprises2-(2H benzotriazole-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol,2-hydroxy4-methoxybenzophenone, mixtures of2-[4-((2-hydroxy-3-dodecyloxypropyl)-oxy)-2-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazineand2-[4-((2-hydroxy-3-tridecyloxypropyl)oxy)-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine,mixtures of poly (oxy-1,2-ethanediyl) andα-(3-(3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxyphenyl)-1-oxopropyl)-γ-hydroxy,α-(3-(3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)4-hydroxyphenyl)-1-oxopropyl)-γ-(3-(3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxyphenyl)-1-oxopropoxy),2-(2-hydroxy-5-methylphenyl)benzotriazole,ethyl-2-cyano-3,3-diphenylacrylate, or phenyl salicylate.
 189. The lensforming composition of claim 159, further comprising an ultravioletabsorbing compound for inhibiting at least a portion of ultravioletlight from being transmitted through the eyeglass lens during use,wherein the ultraviolet absorbing compound comprises2-(2H-benzotriazole-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol.
 190. Thelens forming composition of claim 159, further comprising an UVabsorbing composition for inhibiting at least a portion of ultravioletlight from being transmitted through the eyeglass lens during use,wherein the UV absorbing composition comprises a photoinitiator and a UVabsorbing compound.
 191. The lens forming composition of claim 159,further comprising a dye to form a background color within the lens.192. The lens forming composition of claim 159 further comprising a UVstabilizer for inhibiting degradation of the cured monomer caused byexposure to ultraviolet light.
 193. The lens forming composition ofclaim 159 wherein the lens forming composition is curable to asubstantially aberration free lens in less than about 30 minutes.
 194. Amethod for making a plastic eyeglass lens, comprising: placing a liquidlens forming composition in a mold cavity defined by at least a firstmold member and a second mold member, the lens forming compositioncomprising: a monomer composition comprising an aromatic containingpolyethylenic polyether functional monomer; and a photoinitiatorconfigured to initiate polymerization of the monomer composition inresponse to being exposed to activating light during use; and directingactivating light toward at least one of the mold members to cure thelens forming composition to form the eyeglass lens.
 195. The method ofclaim 194 wherein curing the lens forming composition comprisespolymerizing the monomer composition.
 196. The method of claim 194wherein directing activating light to the lens forming compositioncomprises applying a plurality of activating light pulses to the lensforming composition.
 197. The method of claim 194, further comprisingapplying a hydrophobic coating to the eyeglass lens.
 198. The method ofclaim 194, further comprising applying a hydrophobic coating to theeyeglass lens, wherein the hydrophobic coating is adapted to inhibit theeyeglass lens from being exposed to water and to ambient oxygen. 199.The method of claim 194 wherein the first mold member comprises acasting face and a non-casting face, and further comprising placing afirst hardcoat layer upon said casting face and a second hardcoat layerupon said first hardcoat layer prior to placing the liquid lens formingcomposition in the mold cavity.
 200. The method of claim 194 wherein thesecond mold member comprises a casting face and a non-casting face, andfurther comprising placing a material capable of being tinted upon thecasting face prior to placing the liquid lens forming composition in themold cavity.
 201. The method of claim 194 wherein the second mold membercomprises a casting face and a non-casting face, and further comprisingplacing a material capable of being tinted upon the casting face priorto placing the liquid lens forming composition in the mold cavity, andfurther comprising applying dye to the material to tint the lens formingcomposition.
 202. The method of claim 194, further comprising applyingan adhesion-promoter coating to an inner surface of the first moldmember and an inner surface of the second mold member to substantiallyadhere the lens forming composition to the first and second mold membersduring use.
 203. The method of claim 194 wherein the activating light isremoved from the mold members when substantially all of the lens formingcomposition has reached its gel point.
 204. The method of claim 194wherein the activating light comprises a first intensity, and herein theactivating light is directed toward at least one of the mold membersuntil substantially all of the lens forming composition has reached itsgel point, and further comprising directing activating light having asecond intensity towards at least one mold member to cure substantiallyall of the lens forming composition, the first intensity being greaterthan the second intensity.
 205. The method of claim 194 wherein theactivating light is directed toward at least one of the mold membersuntil substantially all of the lens forming composition has reached itsgel point, and further comprising inhibiting the activating light fromfurther being directed toward the mold members, thereby allowingsubstantially all of the lens forming composition to cure.
 206. Themethod of claim 194 wherein the eyeglass lens is formed from the lensforming composition in a time period of less than about 10 minutes. 207.The method of claim 194 wherein the eyeglass lens is formed from thelens forming composition in a time period of less than about 30 minutes.208. The method of claim 194 wherein the first mold member is spacedapart from the second mold member by a gasket, and further comprisingremoving the gasket subsequent to directing activating light to at leastone of the mold members to expose the lens forming composition toambient air for approximately 5 to 30 minutes, thereby cooling the lensforming composition, and further comprising directing additionalactivating light toward at least one of the mold members to at leastpartially cure the lens forming composition.
 209. The method of claim194, further comprising heating the cured lens forming composition to atemperature between approximately 100° C. to 120° C. for approximately 3to 15 minutes subsequent to curing the lens forming composition. 210.The method of claim 194, further comprising placing a filtersubstantially adjacent to at least one of the mold members, wherein thefilter comprises a varying thickness such that the filter varies anintensity distribution of activating light across the mold members. 211.The method of claim 194 wherein an amount of activating light isdirected towards the mold cavity, and wherein the mold cavity comprisesa temperature, and wherein the amount of activating light directed tothe mold cavity is a function of the temperature of at least a portionof the mold cavity.
 212. The method of claim 194 wherein directing lightto the lens forming composition comprises applying a number ofactivating light pulses to the lens forming composition, wherein thenumber of light pulses is a function of a change in a temperature of thelens forming composition over a period of time.
 213. The method of claim194 wherein directing light to the lens forming composition comprisesapplying a plurality of activating light pulses to the lens formingcomposition, wherein a duration of the light pulses is a function of achange in a temperature of the lens forming composition over a period oftime.
 214. The method of claim 194 wherein directing light to the lensforming composition comprises applying a plurality of activating lightpulses to the lens forming composition, wherein an intensity of thelight pulses is a function of a change in a temperature of the lensforming composition over a predetermined period of time.
 215. A lensmade by the method of claim
 194. 216. A lens forming composition curableupon exposure to activating light to form a plastic eyeglass lens,comprising: a monomer composition comprising an aromatic containingpolyether polyethylenic functional monomer containing groups selectedfrom acrylyl or methacrylyl; a co-initiator composition configured toactivate curing of the monomer composition to form the eyeglass lensduring use, the co-initiator comprising an acrylyl amine; and aphotoinitiator configured to activate the co-initiator composition inresponse to being exposed to activating light during use.
 217. A methodfor making a plastic eyeglass lens, comprising: placing a liquid lensforming composition in a mold cavity defined by at least a first moldmember and a second mold member, the lens forming compositioncomprising: a monomer composition comprising an aromatic containingpolyether polyethylenic functional monomer containing groups selectedfrom acrylyl or methacrylyl; a co-initiator composition configured toactivate curing of the monomer composition to form the eyeglass lensduring use, the co-initiator composition comprising an acrylyl amine;and a photoinitiator configured to activate the co-initiator compositionin response to being exposed to activating light during use; anddirecting activating light toward at least one of the mold members tocure the lens forming composition to form the eyeglass lens.
 218. A lensforming composition curable upon exposure to activating light to form aplastic eyeglass lens, comprising: a monomer composition comprising anaromatic containing polyether polyethylenic functional monomercontaining groups selected from acrylyl or methacrylyl; and aphotoinitiator configured to initiate polymerization of the monomercomposition in response to being exposed to activating light during use.219. A lens forming composition curable upon exposure to activatinglight to form a plastic eyeglass lens, comprising: a monomer compositioncomprising an aromatic containing polyether polyethylenic functionalmonomer; a co-initiator composition configured to activate curing of themonomer composition to form the eyeglass lens during use, theco-initiator composition comprising an amine; and a photoinitiatorconfigured to activate the co-initiator composition in response to beingexposed to activating light during use.
 220. The lens formingcomposition of claim 219, further comprising an activating lightabsorbing composition.
 221. The lens forming composition of claim 219wherein the photoinitiator composition is configured to form a polymerchain radical in response to being exposed to ultraviolet light duringuse, and wherein the polymer chain radical reacts with the co-initiatorcomposition to form a monomer initiating species during use, and whereinthe polymer chain radical and the monomer initiating species react withthe monomer composition to polymerize the monomer composition duringuse.